Ramp Door

[BPD25]

I have a 27hfs and plan on using to haul my 05 Golwing. The bike weighs about 900lbs. I have loaded the bike into the garage area a few times and I am not sure if it was the weught or heat there is small groove in the door where I ride the bike up. I am wanting to reinforce the door in that area with a strip of plywood. I don't know what the composition of the door is, and what can I fasten the wood to. I assume the door had metal studs but not sure.
Thanks,
Brian

[popik]

I cant say for sure but i think mine is framed with aluminum and has the fiberglass outside with a foam center and thin plywood inner