I also did mine with the Henry's 887 Tropicool recently. Very happy with it but it is very smooth & slippery when wet.
18 year old roof here however each year it had spent 7 months indoors so the roof was in better shape than a similar than an always exposed roof.
Similar prep. Washed it with same soap that it, & rest of the the trailer, gets used. Followed that with about 50% clorox & water mix to kill off some of the black trailer pox marks.
Cut around edges with brush going over original caulking to give an added seal. Finally rolled the rest. 1 coat. 2 gal covered roof & slides of a 35' 5er.
