there is a way you can do it yourself, easily and reasonably.
I have been in the roofing industry almost 40 yrs, seen and used every single product there is for water proofing.
liquid PMMA is the way to go on rv’s, incredibly tough yet flexible, and extremely durable. comes with a 25-35 yr warranty on the PRODUCT, but has a much longer service life. you could beat on it all day with your hammer…you might scuff it.
you want Soprema Alsands RS 230 Flash
i brought a 25lb 5 gal pail home from work, used a 1/4 can for 2 coats, added maybe 7 or 8 lbs to my camper. done forever, spray the pine needles and stuff off every now and then, nothing else to do, one less thing to ever worry about
here’s some info
and here’s what it looks like, and on my camper
oh ya, you definitely want to be wearing HD gloves with this stuff