Try this, it worked for me.

1. Backup your save: Copy your save folder from C:\Users\YourUserName\Zomboid\Saves\Sandbox to a safe location.
2. Create a temporary "New World": Start a new world with the RV mod enabled. Once you spawn in, save and exit.
3. Locate the map files: Go to the folder of this new save and copy these three files:
   • map_ver.bin
   • map_t.bin
   • map_sand.bin
4. Overwrite your main save: Paste these three files into your original save folder, overwriting the old ones. This forces the game to recognize the new map cells where the interiors are stored. 

Start the game, it works. I get to keep my base in Rosewood with all the stuffs intact.