First of all, I look forward to seeing this build come along. I like Rohlan and his armor is great. My first set of armor used a modded Rohlan helmet. I still have it sitting on my self. It was retired after Karen Traviss signed it.
We do have CRL's for KOTOR Crusader Era Mandalorian and Rohlan would fall into them. We don't have a specific Rohlan CRL however, we would evaluate any build based upon the existing artwork. I understand your dilema. I built a Mandalore the Indomitable, from teh Sith Wars comics, and he varies in appearance almost from frame to frame, let alone issue to issue or artist to artist. What I did was look at all teh existing artwork, pull specific stand out items that didnt vary or varied little and then looked at other stand out features in the various artwork. What I ended up with was a build that was consistant with the character overall and had pieces specific to certain sources although, the costume as a whole wouldn't stand up to any one source. The end result was undeniably and obviously Mandalore the Indomitable. I would suggest taking a similar direction with Rohlan. Take what y ou like from certain sources and leave behind what you don't. As long as the end result can be looked at and know to be Rohlan, you've done your job.
Now as for your question directly. Most source I would say that it is clearly a single torso plate, perhaps two that overlap at the ribcage like clone or TK armor. However, in teh picture you've sourced, that's not the case. It really does look like an early flak vest design. Much more practical for movement and probably costumeing as well. However, from an in-universe perspective, it wouldn't offer the same level of protection.
My opinion for you would be to do it as you like. Build it so it's quality built and clearly Rohlan and you won't miss the mark!
