Hi Peggy,
I can only share my experience, why we choose full body paint, and why we still like it.
We owned an unpainted fiberglass rig for 24 years. It was hard to keep it looking nice. As the years went by, it looked worse and worse. I would put so much hard labor into the thing to have it look mediocre. The first 5 years we owned it, we parked it outside. The last 19 years we owned it, we kept it in a garage. I think some of the problem with unpainted fiberglass has to do with age, not just weathering. We sold that rig in early 2007.
While it was for sale, we ordered our PC, I convinced my wife that because we will keep this one in a garage from the beginning, the paint work should be a good investment. Not only to look nice, but to clean easy. Our PC is 11 years old and the rig looks almost new, and it does clean easy.
In our case it was a really good investment. But remember that we keep our PC in a garage when not traveling in it. I hope others with full body paint and a long history of 100% outdoor ownership will report in with how their full body paint is holding up to the elements.
I have thought that if I wanted a plain white PC, it would be worth painting the whole thing the same white as the Ford van portion. It should be a lot cheaper painting it one color, and not needing to paint the van portion. I assume it would be very affordable. The entire rig would be very easy to clean, and would age very well. I also think going with a solid color would open up opportunities for other color choices, but you would likely need to include the Ford van portion to look right.