carpet
When I did my old trailer I worked at a bass boat factory and I got out the spray gun and glued my carpet down. I would suggest using Marine grade carpet. it has a rubber backing with very short carpeting on it and will stand up to a lot of abuse and is weather proof. you can get it in reg carpet stuff or the plastic astroturf i like the cloth better as any oil gets on the astroturn it is harder to get out go figure. last i checked the cloth type marine carpet ran between 7 and 13 dollars a sq foot.
joe