I don't know how Scamps are set up...I'm guessing there are already light
fixtures? Or no? If there are light
fixtures already, then the holes are already drilled and wires already run, and you would just want to find fixtures that fit those pre-drilled holes.
If they aren't already run, I'm not sure. My camper has wood walls and ceiling so there's something to drill into other than the fiberglass body. There are battery
powered, stick-on lights
out there, too. Depending on where you wanted the lights, I think you could avoid drilling. I have to assume there are lights in there already, though...
I usually just replace the incandescent bulbs with LEDs. Sorry, I don't have Scamp-specific knowledge.