Vhonte Tervho is no longer Canon, but even when she was, she still had a vest. It just matches her flightsuit.
I have to respectfully disagree with your assessment of her outfit. I own a copy of that issue and have scrutinized those images of her, and there is no vest. There’s no demarcation or change in thickness at her belt or at the shoulders, showing a vest over her flight suit, nor is there even any unbroken line across her abdomen suggesting a vest worn over her bodysuit. There are only typical seams at the shoulders and down the sides where the stitching is in a one piece body stocking, where the parts were sewn together, with smooth lines and curves, and wrinkles where her todo twists. This is especially clear in this image:

Not even her action figure (also used for Arab Bralor) included a vest in the sculpt:

There is
no vest. Her armor is attached directly to her
flight suit.
Both Paz and the Armorer have vests, they are just not the same type as the classic ones for Boba or Jango. Paz, in particular, is “sleeveless”, or without shoulder bells.
I just looked at a few images of Paz Viszla’s costume, and he’s not wearing a sleeveless vest. Just the opposite. It’s a dark grey quarter sleeve shirt over a light grey padded suit. Whether that’s considered a “vest” is a matter of semantics. Here’s an image:

The Armorer too appears to possibly be wearing two shirts, a quarter sleeved one over a long sleeved one, or simply a double sleeved shirt.

I don’t see any vests on either of them. Then there’s Vera Beroya from the AoR module Friends Like These. She too lacks a vest. She wears a full wrap-around cuirass that’s connected front and back, with a separate ab plate below it attached to her suit.

Boba... well, let’s wait till after the new year; give the CRL Team time to work out wether or not to allow certain aspects to be used in custom builds.
I hope so. FYI, this was my first armor made last year:

My original concept was to use my duster
as my vest. Like I said, I’m an artist, I like to think outside the box, and I like repurposing even my everyday clothes in my costumes.

The Rebels Grunt isn’t wearing a padded vest. And Sabine. Wearing her plates the same way she does is only applicable for HER SPECIFIC CHARACTER. Anyone wanting to use her plates in a custom build needs an ab plate, collar, and a vest.
I also disagree on the grunt. The image looks to me to show a definite thickness with a sharp separation running vertically up his side showing the “vest” to be much thicker and more rigid than cloth or soft leather. To be fair, that could be a shadow of his arm.
Sabine’s mother, as well, does not wear a vest. This is clear in this image:

In fact, based upon other images of her, her outer garment appears to be a
full-sleeved, mid-thigh length tunic; it’s not a “vest” at all. The skirting is attached to the top. It looks to be all a single garment, not a vest, loin cloth and Kama.
My point is that we see
multiple Mandalorians, in both canon and Legends, who
don’t wear a flack vest. Sabine
isn’t the only one, nor is she the first. She’s just the most
blatantly obvious one.
Ideally, I prefer the clean look of a full cuirass, buckled at the sides, without a vest underneath, or with my duster underneath, but, failing that, there is no restriction on how thick, what style, or from what materials a ‘flack vest” has to be made, according to the CRLs. Given that choice, I prefer the look of a
proper military style futuristic tactical “Kevlar” flack vest, rather than just a layer of heavy cloth or leather.
However, I’m not about to shell out several hundred dollars on a real MOLLE/tactical vest, or a real Kevlar bulletproof vest, that itself would need further modifications, when I can make my own custom design “sci fi tactical vest” from foam. So any vest I make would be along these lines in solid black:




In other words, actual semi-soft body armor.
One thing about
most Star Wars “armor”, It isn’t functional armor and provides
little to no protection, not even hard armors, such as Stormtrooper armor. Beskar’gam is really the only armor in canon that really does what it’s designed to do:
prevent damage. I want something that looks like it actually provides protection (if it were real) not simply something to hang some plates on.
Ideally, I’d rather turn my plates
into my vest, a full cuirass, not independent plates just stuck onto cloth, and since the CRLs do allow straps to be used to secure the armor, vest or no, I’m sticking with that full cuirass held together with webbing between the plates and secured at the sides. That allows me to wear it
with or without a vest or other “outer garment” between my cuirass and my BDUs.
It’s good you know ABS, as that is an approved material. You should also know that at the thickness needed for making the armor, heat warping is not as big a risk. I’ve helped build a friend or two’s TK, and my wife’s kit is ABS.
Yep, though mostly in the form of detail pieces and ABS angle and I beams. Mostly I worked with sheet styrene, and even then, only up to a thickness of maybe 2mm.
The reason why most modern kits are reminiscent of Jango and Boba is because they are the very definition of a modern kit. However you’d be pretty hard pressed to confuse my kit or many many other kits with either Jango or Boba.
The CRLs are there and that’s what we all have to follow there’s no going around them. And until they are updated it doesn’t matter what we see in shows like The Mandalorian, if something violates the CRLs then it simply can not be on an approved kit.
There are many options to customize however, for instance. If you want a thicker more padded vest that’s totally ok, I’ve seen that look accomplished by adding quilting to the vest (Boba’s vest is like this). If you want all your torso armor attached by strapping that’s ok too, we have someone in our clan using that method. However that strapping must meet certain criteria.
The fact remains if you want to build a modern kit a flack vest is specifically called out in the CRLs.
Remember we all want to help you become official.
I understand that. I’m simply pointing out that there
are multiple different canon and Legends Mandalorians who break even that one CRL regarding the vests, in particular. Sabine Wren isn’t the only one, and not even the first.
And, while the Fett’s are certainly the “prototypical” iconic look, theirs is certainly not the “only” look nor even the most common any more. Shouldn’t the CRLs take that into account?
And some of the restrictions, such as “no back pockets” rule, don’t make sense
from a practical perspective, as a military veteran. As a soldier, you want pockets. Pockets are a good thing, and very useful. You can’t carry everything on a utility belt or LBE. This is especially true of military style pockets with a flap cover, (below) as opposed to those found on jeans, I can understand those being forbidden.

Just because neither of the Fett’s had back pockets does not mean that no Mandalorian could, or would, have them.
My understanding of the criteria is that any strapping cannot be made of elastic unless it’s hidden completely under the flight suit (except at the knee and the thong securing the cod piece between the legs), but that nylon or leather straps
can be exposed. The straps used to secure my current cuirass together is
nylon webbing buckled at the sides. That does meet that criteria. So whether people can see the straps between the plates isn’t an issue.
Like I said, my top priority is to create a badass suit of Beskar’gam that fits my vision, even if it doesn’t meet the criteria for official membership. If that does coincide with the CRLs, so much the better, but it’s not absolutely necessary right off the bat, especially since, without a car, my chances of trooping on a regular basis, especially outside of Buffalo, is slim to nonexistent, for the foreseeable future. So having something that looks badass for cosplay and Halloween at reasonable cost is of higher priority. I’ve already spent more than expected on this kit as it is, and a good chunk of that was in soft goods, and tools, including a brand new airbrush and air compressor. So, I want to get the most use out of my current kit as possible before upgrading to a new kit, even if it’s not up to standards for approval yet. I want to get my money’s worth.