I want to coat my roof as I have ownwed my coach for two years and have not done this. I figuer it would be a wise thing to do. Any suggestions on what to use. I used some stuff on my previous RV that the parts dealer suggested although it left white streaks down the sides when it rained several weeks later. I would clean them up until next time it rained. Was thinking something that would be more of a rubber consistency when it dries. Thanks.