(These are mostly personal musings on problem- I'm not explaining it explicitly enough to describe it for others currently [primarily because I think to really explain, I'd have to draw diagrams, and I'm still not sure how well I could translate 3D deformed space to 2D flat and still retain any sort of clarity]. I'm still looking around for potential solutions, but am just coming up with more problems instead.)
Upon further research, the wall gets taller. Apparently there are a number of imperfect tools out there to try to get around the problem (including one that takes an obj and imports it as a sculpt through the SL menu...which, aside from the fact it's extremely touchy on what you can ever try, I generally don't trust at _all_), and it sounds like they all do it badly. There's a big discussion on the forums about trying to do it and how tos in ways that...I just don't understand why they're trying to do it _that_ way, as it seems like the hard way to me. Looks like Blender is not the only program to not map proper though (no programs were raised as "well, you know x does it right, even if it is expensive" which isn't really heartening. If Maya actually got around it without all the hoops and etc....)
Tacked on, I'm not 100% sure I'm on the right page with the way SL does it. Mostly I'm a little perplexed as to texture mapping regarding, as they seem to be at odds to me (which is another dimension of The Problem with inaccuracy). At least in certain ways- it mostly comes down to "well, you stitch it this way and I get it. But you stitch it that way and I'm starting to get a little confused." There's also one more somewhat esoteric and bizarre stitching method I'd love to have, just generally (a modified sphere stitching, basically. It's odd and strange enough although it makes sense while modeling that I can't see it even being something they would consider adding, as much as it would be useful).
Worse, in regards to my immediate problem...I'm not sure where I stand on that at all. This is not 100% due to the inaccuracy problem (now, raise the prim limits to 20x20x20, and I wouldn't have any of that dimension at all, because I wouldn't have to worry about splicing bits and could skip my problematic steps. *sigh* I wih megaprims came in more useful sizes, and the massive chunk of them weren't just hacked to make it work in one particular manner this way, which means it won't with anything else), but also due to a bit of uncertainty how to actually approach certain features of the object itself. This is a point at which existing architectural reference would come in handy, as I'm not sure how x and y would translate properly, nor how much they would be desired. So yeah...spinning my wheels entirely until I can get a concrete vision on what I'm doing.
Tacked on, the thing for me...I'm still very heavily in the "that would be a nice thing to have" mode, not really the "ok, let's do this!" It's another thing that I need to wrap my head around the scale of before I can get much done, and I'm just...not sure at all. At least a) it's something that there is architectural reference of, even if I am not going those ways a lot, and b) I've already figured out how a fair bit of that will function regardless, prims willing.