[Ed in Maine]

There could be many suggestions on this topic. In the past I have used 2 coats of Ebony Stain and three coats of spar varnish (sanded between coats). While you are at it why not add a heat baffle to the underside of the floor board to keep the exhaust pipe heat out of the car. My heat baffle is a small sheet of aluminum from Home Depot and 1 in. stand offs to provide an air space between the aluminum sheet and the plywood. Have fun with it. Ed