Glad it's working for people.

Same as the KLAS problem...the whole strip sits up on a ledge just like KLAs did before your file fixed it.
The file VEGAS2004TR.bgl controls the main flattening. Disable that and the plateau is gone. Unfortunately, that leaves various items floating in the air... Including some kind of UFO, but that's another story. The same thing that worked for KLAS could work for the rest, but the very tricky part is getting the two to work together. Or to extent the KLAS files to encompass the Strip as well, but either is gonna open a can of worms... Maybe contact the author, a package without roads (the main objects that need a flat terrain) and elevation values for other items should sit on top of whatever elevation.