Do a search on this forum, I think I posted something about my mods a while back. I have pictures around here somewhere... Full and past vertical stern squirts in a 12' boat is a beautiful thing.
------
Just did a search, maybe I didn't post it before!
0. wait for a warm day
1. pull out saddle, stern wall
2. cut wall to desired prfile - I cut it to about 2" thick for most of the length (cutt off top side)
3. put glue (not contact cement - I used Goop) on wall, reinstall wall
4. compress boat - I used plywood, 2x6s and a truck
5. paddle on
I would in the future improve the mod by making the wall stiff - not sure how just yet - glass? sheet of plastic? The boat turned out a little floppy, so I paddle it conservatively. The cockpit is still solid, you can feel the stern flex some, though... Also the hull, after a while pulled *up* from the bottom, interrupting the natural shape and probably slowing me down. But for cheap fun, it has been a blast.