Thanks for the tip on the install pack. Leonardo is working on a new version of the BWP package to help handle this mod overhaul, but maybe this can help others in the meantime.. I'm fairly sure the Fixpack fixes are no longer needed in BPv181, so don't worry about that for now.
I accounted for it in the version of the Big World Install.bat I posted in another thread, and it recognized BP (181+). However, I must have made some other error, because on occasion it did not install BP despite recognizing it. That's why I'm also waiting on Leonardo's revisions. He is definitely the master of his own filepack. I'm just a good-intentioned, fumbling interloper by comparison.