You can get some marine plywood to replace your floor with.Then one of the fishing supply places.(3rivers?)should have the vinyl.They are both spendy.I'm not sure of a price for the plywood.But Fishermans in portland wanted about $22-$25 a yard for the vinyl.
I ended up using outdoor carpet for about $4 a yard.Not in my sled though.This was for a boat we use at the canal.
Some of the other guys here might have some better ideas.Aluminum maybe.