Kool Seal would work, and if the roof is metal you can use the regular Kool Seal instead of the RV version (which is for use on EPDM roofs).
Dyco #890 is another such product. but a Lowes or Home Depot will have a selection of products for metal roofs. Henry's is another top name in the roof coating arena.
Former owner of 2004 American Tradition and several other RVs
Home is West Palm Beach, FL