You can use Liquid Roof or its twin Liquid Rubber that is a tad lower in selling price.
Your roof being black is a NON issue to keeping your RV dry for another 20 years of you keep all the seams sealed with Eternabond, etc.
Keep in mind 99.9% of roof areas covered with EPDM rubber is done with BLACK. White it only a thin finish to help reflect some of the sun's energy. It does not make the roof last longer. EPDM in black or any other color is very UV resistant by design.
Again black is just fine for keeping an RV dry. If you are going to used Liquid Rubber or its twin I strongly suggest you deal all of your seams and openings with Web Seal version of Eternabond so you have them addressed for the next 35 years. It is glass backed and needs to be coated anyway.
Shops around here charge around $100+ per running foot of the RV length if there is NO water damage to address.