Has anyone found a way to help better protect the bottom of the hull?
I don't care much for scratches either -- they look unsightly and slow the boat down. For exposed bottom surfaces, clear shipping tape is tough, easy to apply/replace and inexpensive. It will take the abuse on wearing surfaces instead of your hull:
Wheels go on and off in the water so the boat rolls in and out without touching the ground. You can also use the wheels to act as a parking brake without having to beach the boat for short trips ashore (with obvious limitations):
Any place the boat needs to be set on the ground, a small carpet sample goes between the boat and the pavement.
For scratched surfaces, a razor blade trims off any material that sticks up. Scratches can also be "flamed" off, but it's a tricky process.
With a little practice and advance planning you can keep that boat looking new for years!