Took my class C 31 ft in today to have a sealtech leak detection done. This is a coach that has not leaked a drop but wanted to be proactive. Was told the tech had a concern and it would be $1300 to...
If there is a Rhino Lining place, it may be expensive, but the price is about the same as a new rubber roof, you might look at having them spray a coating on the top... the nice thing about their product is that once on, no need to worry about Dicor or Eternabond. One does have to check if the roof got punctured by branches every so often, but leaks are a thing of the past.
I'd highly consider this option as an alternative to the rubber roof.