Instead of using ordinary coatings use RV Roof Magic. First it can be applied over any type of RV trailer or mobile home even if there is a 3rd party coating applied over the original roof. There is a built in mildewcide to deter mold from growing on the roof and it has a very high percent of volume solids a high tensile strength making it hold up in all types of temperature extremes. Comes with a 5 year warranty and is easily applied with a long nap roller.