I used the lowes indoor outdoor carpet with the rubber backing and it seems to be doing ok. With what I bought you have to be careful with the hooks snagging but it's not that bad. I found a 12'x12' remnent for I think $40.
I called my agent the other day and she said the boat and trailer while hooked up to the truck was covered by my truck insurance and when i'm on the water it is covered by my homeowners. I didn't ask specificaly about liability but i will tommorow.