RV Interior is a popular mod that adds interiors to over 100 vehicles in some mods. This mod adds 25 customizable spaces, with power that's tied to the car battery, and different entrances depending on the type of vehicle with an interior. This mod is awesome for an immersive experience and if you want to spend a lot of time travelling around Kentucky with a lot of gear and necessities on hand. Here's how you can install this mod on your server.
1. Open the Advanced Server Settings
2. Find the line that says Mods= and list RV_Interior_MP
3. Find the line that says WorkshopItems= and list 2822286426
4. Find the line that says Map= and list vehicle_interior
before any other maps.
5. Restart the server.
RVs and other vehicles will now have accessible interiors.
Check out this post for a full list of supported vehicles and mods with interiors.