My Fleetwood was build with curved rubber roof from the factory, but than Lance with its 1- sheet aluminum and additional trim sealant hold for 20 years just fine, even the flat roof sag over the years and after a rain water would stand on the center for days.
I could not keep rubber roof sealed for long time as caulk would not stick to it, till Henry silicone roof sealer come to the market few years ago.
That stuff covers everything and sticks to it. Making 1 uniform coat- you can see where it shrinks over gaps and need additional layer.
The hardest part was to seal Eterna bond applied by PO.