Have you ever cleaned it? I think keeping it clean is the best thing. Years ago, dicor advised that the only thing you need to do to EDPM roofs, was to clean it. You can clean it with a commercial rubber roof cleaner, or a non petroleum cleaner like non bleach powder laundry soap mixed in a bucket.
I use non bleach powdered soap. i mix it in a bucket and mop it on the roof. i use a really soft bristle brush and lightly scrub. Rinse. Then clean the sides of your camper and rewax the sides of your camper.
After they discovered they had a market for products, dicor came out with rubber roof conditioner, that you can mop on with a sponge mop after cleaning.
Orginally dicor stated that there was no need for anything on a rubber roof other than cleaning. They now produce a roof conditioner. I am not convinced its not just marketing.
There are 2 types of rubber, TPO, and EDPM. The EDPM will powder a bit over time.
The best thing in my opinion , is to keep it clean, under a shed, out of the sun, and inspect and recaulk the seams, penetrations as needed. Use dicor caulk.
I go on my roofs bare foot, so i don't tear the room turning with shoes on, or leave black marks from the shoes.
Whatever products you use, research them to make sure they are not made with any petroleum ingredients. Or buy the Dicor brand.
I have been cleaning it and using the conditioner. but I thought it might be a good idea to put on a rubber roof coating.