Hef,
I have a fiberglass boat and fish in the trees with no problems. I get a scratch here and there but nothing major!
Here is a trick for you to try before youget rid of your boat:
Get some 1 1/2" PVC pipe(scd 40). Cut a couple in 5' lengths and a couple in 10' lengths. On each piece at one end drill a hole in the side close to the end. Get some rope and run it through the hole from outside to inside and tie it off. With the other end of the rope, run it down the pipe to the other end. This will allow you to make a loop at the tied end to put around the brush. At the other end, leave about 4 ft of rope and cut it off. Now you have a way to tie off to the brush without getting into it and tearing up your boat.
I have 2 sets of these made and they work great. Works best for me if I use one off the bow and the other off the transom. Not all situations are the same and therefore this doesn't always work the way you would like it too. I use them to tie up to bridge pilings and brush.
Need anymore info on this, let me know!
Greg