I used what roofers use for EPDM and TPO, worked great. Also read their case study's.
http://inlandcoatings.com/case-study/First gallon I got from RV place and paid $112.00 following year I called around roofing places $48.00
Also talked to their corp and local sales rep about tinting (no problem) and corp gave me a few hints. Brush on is so much better coverage in little tiny spots you won't see using a roller but of course you use more. I'm very happy after several years. The more you clean before use the better off you'll be.