RV Repair: Rubber roof repair, rubber roofs, roof leaks

Question
I've recently purchased a 1991 25' terry resort.  Roof leaks existed but have managed to stop most with caulking or patches. I am having extreme problems with the edges running along the length of the trailer. In some areas, the roof is tearing along the metal bracket which I assume serves two purposes. One to clamp the rubber roof and two act as a channel drain for run off.  I am thinking of removing the whole metal bracket and run a 6-8" patch the length of the trailer. My question is if I remove the whole length of metal, will the pre-existing rubber roof snap off due to tension? If not, should I cut away the pre-existing rubber roof where I plan on patching or just lay the new rubber over the existing?  

Answer
1) If the existing roof was glued down properly, then you should have no problem with it moving on you. The reason it is tearing is probably because it is simply getting old and brittle. Rubber roofs need to be treated every few years. In fact, it would be hard to get it off because of the glue . Which leads us to the second question.....
2) It is fine to overlay the existing roof, especially if the existing one is glued well.

Dave