I rebuilt my coleman roof two years ago and used Tremco Vulcan 116 which is a great polyurethane caulk for RV's. You will need to remove all the old first which can be quite a chore. Once the new caulk had cured (3-4 days) I then covered the entire roof with two coats of Sherwin Williams (I'm sure there are other manufacturers that would work just as well) high quality oil based primer, once dry I then used SW high grade exterior white satin latex as a final finish (3 coats). I applied the primer and paint with a roller. The primer covered the caulk really well so the entire roof had the same color when finished. After 12 camping trips it still looks brand new without one blemish. The caulk has not split and the paint still looks as white as snow. Of course I keep it parked in my basement when not in use
I ended up stripping all the old decals and painting the entire camper. Here's a link for the Vulcan manufacturer: www.tremcosealants.com/commercial/products/product_detail.asp?id=1
Maybe you can find a dealer near you on there site.