Let me tell you what I did as I am not familiar with the product you mentioned . I also have an older Sunline travel trailer that had a leaking roof . First I removed all the roof vents , covers , etc . Second ,I removed all the old cracked caulking , cleaned area then used Dicor self leveling sealant , used 4 tubes . Third , I washed roof with a special cleaning solution to prep for Dicor rubber roof coating , used 2 gallons . It has been only 3 years since the work was completed and the roof still looks brand new . I have just a little water damaged in the bedroom ceiling corner , this work stopped that from getting worse . Very satisfied with the products I used .