CHEAP!
I found some really cheap 1/2" thick plastic cutting boards at a local outlet shop and ended up using two of them for stern rail seats. For each seat, I used one cutting board, and one pair of the white plastic 1" rail clamps. These are the ones that screw on with a large black plastic wing nut. They are attached to the lower rail just beside the swim ladder opening. I made a single support leg which supports the front edge on the cockpit coaming. I made the support legs by cutting them from third cutting board. When sitting on these seats, you can lean against the top rail of the stern pulpit and rest your feet on the normal aft seat. I might make some small cushions to cover these rails for more comfort, but it isn't bad as it is. They are very comfortable, provide a much better view and still allow the aft seats to open for access to the stern lockers. They even make sitting on the original aft seats more comfortable because the front of the rail seats provide a convenient back support while sitting on the lower level. There are now three levels of seating along the back edge of my cockpit, the two outside seats on the original bench, then just up from that the hump of the helmsman's seat, then up from the two stern rail seats. I had to cut a small section from the inboard rear of the port seat to allow for the welded on stern light, but otherwise the fit was very straightforward. So, the bottom line ... I spent $6 for each of the cutting boards, $16 for each set of rail clamps and about a buck for S/S screws to attach the legs to the seats. Total for both seats ... about $50. I'll post a photo in the photo forum as well. Gary