@All: Speaking of 1.9.1, I've got that and the AWLS 5.4.0 meshes embeded into my custom BSA again, and I've fast traveled the map at random, into cities and out. No issues. I've trekked on foot through the wilderness from city to city, passing through most of the middle section of the game and arcing across the north. No issues. I am therefore entirely stumped as to what was causing the problem that was generating guaranteed crashes with the same material not more than a few days ago. I certainly haven't done anything to change my OSR configuration. So as they say, W T F?
I'm going to package the update to 1.9.1 as a separate archive for now and stick it up on Nexus. I'd like folks to try it out, see if it generates issues. If it crashes, then we know what caused it. If it doesn't, then holy crap, who knows.