In the dark, light travels from the source and reflect off the camper surface to your eye. It's called the angle of incidence. If there's an imperfection it reflects light in another direction. Light during the day comes from all directions, so your eye will see light reflected toward it even at the points of imperfection.
Search for info on ZEP. It's an acrylic coating(floor sealer). You wipe it on and let it dry. You have to put on about 3 thin coats(depends on how rough the surface) and it will start to look good.(It fills the imperfections)
It's sold at many stores including Lowes. Requires clean fiberglass to adhere good. Lasts about a year.(for me anyway) Can be remove with an Ammonia based floor stripper.
For me, makes cleaning the bugs after a trip very easy. I scrub the front with a scotch bright pad( which removes some the coating) and then put another coat of ZEP on. Much easier than scrubbing and waxing.