Just forget about it if you have the leak stopped.I think the tech that told you you would have to replace the entire roof is an idiot. Be careful there are a lot of them running wild here in America. I have never heard of replacing an entire fiberglass roof. Now rubber roofs on travel trailers and such are changed in one piece. I have a couple of areas that I have repaired that have de-laminated and rotten wood around the area. (bathroom skylite bubble) There are a couple products, one being MinWax "Wood Hardener" that are very thin epoxy compounds that can be used during the repair but if the leak is stopped just avoid stepping on the area and keep an eye on it.
2005 Sun Voyager Workhorse W24 with 8.1 ltr Chevy. Allison 2100 transmission. Full body paint.