*Load into existing save* Don't know if this has been mentioned, seems to work for me in a sense. Able to build new basements at least. Similar to the fix in RV Interiors
-Load new world with mod loaded, Exit the game soon as its loaded
-In save files C:\users\(name)\zomboid\saves *Backup world*
-take the map_ver.bin from new world
-copy and replace into old save
-Find basement book/s then Build your new basements!
Put it as a thread here as only tried this briefly but seems fine so far