We recently had damage to our Coleman Utah and could not find a replacement roof for it. As a result it was totaled by the insurance company but we baught it back, removed the original roof down to the fiberglass and had a company Line-X it. We had the AC put back on and the rubber seal and it was 100% waterproof and looked really nice. I believe it was applied directly to the fiberglass underneath and we did not have it Weighed but I would immagine it added a couple of 100lbs.
While being repaired we found a 25 foot Jayco Hybrid and sold the pop-up last week so I dont know how this would apply to the TT as I am new to them.