My rv dealer uses Dicor self leveling sealant in their shop for maintenance and repairs. It's what they recommend and sell retail. Their parts department stocks the full line of Dicor products for rv roof maintenance.
Dicor has videos on how to apply their product too.
I like how the Dicor product flows out of the gun, I only use rotating barrel pressure release guns, and the way it predictably self levels and covers targeted spaces.
I own a Class C with an EPDM roof and do seam maintenance myself. Last week, I also did seam maintenance on my cousins TT using Dicor on the roof and Geocel Proflex on the side seams. I took a slew of pictures for the record and will attach a few.