Cargo ramp door/ handicapped camper

Hello, I am in the process of building my handicapped cargo camper. But I have a question about the ramp door. I want to know what everyone else has used for the ramp door over the wood. I am going to roller my daughter's wheelchair up the ramp door, and I am looking for a product that is water proof and has good traction to walk up as she is rolled up. I was thinking about the bedliner DIY. I really would love to find the toy hauler black material. Any other suggestions? thanks