As you've discovered, most owner's manuals of RVs aren't worth the paper they're printed on. I always suggest folks crawl and explore every opening and write down make and model of everything they find. Then Google each item and you'll most likely find PDF copies of manuals, parts lists, and troubleshooting guides for each system in your RV.
If the lights don't have switches on each light fixture, then perhaps yours is mis-wired. Often only one ceiling light is wired to a switch at the entrance to see to get into the RV. The others are turned on as needed at the fixture.
The lights should have a 12v fuse or circuit breaker to protect the wiring, if you can't find any circuit protection then I'd haul it back to the dealer and have the wiring checked. According to your level of skills, it's possible to rewire and correct these possible problems.