The actual splicing of the maps and establishing proper collision and event spawn points is easy enough, now I'm just trying to figure out a formula for making the map fully connected, with no inaccessible portions, while still filling the full space.
Took me almost a week, but I finally got everything working perfectly! I was missing a way of validating potential map layouts post generation, but I figured out a way to create a validation key that does exactly that, and now it's done! I have fully procedurally generated dungeons in RMVX that use PARALLAX maps!
I'm gonna make a video about this in the next couple days, once it's up I'll post it here.