There are a couple of possibilities for propane. The most likely is a built-in tank, which means you have to drive the RV to a propane seller (not just a cylinder exchange kiosk sort of place, but one where they sell it in bulk) and they should know what to do if you point out where the tank is. The other possibility is a compartment somewhere with one or two cylinders in it.
In either case, the access would be through some external compartment door. It's probably simplest to just go around opening all the doors until you find it. The propane compartment door should not be a locking door (for fire safety reasons), which is sometimes a useful clue for figuring out which one it is.
For a class C motorhome, the vehicle manufacturer is the company that completed the vehicle, not the chassis manufacturer. No idea who "cave" would be.