jd,
I made floorboards for my 22 and have been very pleased with them. I used 1/2 in baltic birch plywood with red cedar stringers underneath. I epoxy coated the entire top and bottom and painted the topsides with a non-skid marine paint. I used Interlux brand paint called Interdeck polyurethane non-skid finish which I got from West Marine. I highly recommend it. It gives a very good non-skid finish without being too rough on the feet. You can walk barefoot on this finish without any discomfort yet it never has any tendency to get slippery even when wet. Be sure to clean the epoxy coating after curing, rough up the surface with medium sandpaper and use the recommended primer before applying the deck paint. I have used mine for six seasons and they are still like new. I just repainted this year for the first time. Dragging the heavy fish cooler over them did eventually cause a little wear. One quart was enough to cover originally with enough for a recoat later. Somewhere in my photo album are pictures of the floor boards under construction. Good luck with your project.