Ajax - Thanks for the comments and suggestions

I like the creative solution of placing the filter housing in the back and understand that in a sealed suit it wouldn't matter, but would the general population see it that way? Maybe I'm underestimating the fans, but half the fun is making something they can appreciate and enjoy. I think if I did it in the back I would have to maybe over-exaggerate it to make sure someone looking at it the first time would recognize it and not wonder why my helmet had a wart. At that point, I may as well just go with the stereotype and run a hose to my pack. I'm not shooting the idea down, just trying to discuss it. if you think otherwise, by all means say so. I love the idea personally and it would be both very unique and realistic. I'm just not sure it works on a costume.
As for weapons load, I've mulled it over and discussed it with a friend or three and I think I'll go with the setup you seemed to like. Blaster right thigh, long beskad left hip, blaster left back, various tools in assorted places. There was also a suggestion to convert a bandoleer into a tool "belt" which I am pondering.
Regarding the helmet skirt, I had thought to do one that went from the helm's inner rim to the chest's neck line, essentially replace a skin-tight balaclava with a leather one that would drape a bit but I think I have decided against it at this point. Using maille hadn't occurred to me. I saw a pic when I was first getting ideas that showed what appeared to be a mando with a chainmaille cape which looked interesting and oddly incongruous at the same time. Would chain [gorget?] hanging from the helmet to the chest plate [worn over a black balaclava] be in-universe?
Which brings us back to armour design. I've been looking a that sketch for a couple days now and it is just too damned busy. Went back to the drawing pad last night and I'll have something else up soon. Keeping his support role more firmly in mind this time, I am dropping the collar in favor of better vision and flexibility and the plates will be less sculpted. Still going with the full chest with two articulated gut plates and same overall combination of plates, but reworking the chest design. Also found a huge box of colored pencils so it won't be scanned and flood-filled to lose all detail this time :-P