My RV roof is 90% intact with an approx. 12" section that runs along the entire length of the coach and along the passenger side edge. It has deteriorated so was wondering if I could simply remove that entire length of original rubber roof (97 Fleetwood Southwind) back to good material, then roll the liquid roof over the entire remaining rubber roof and ultimately over the plywood section as well that I have removed the original rubber roof sheet from??