My Wenonah Prism (solo) has a pedestal seat in the middle - the 'tractor' or 'bucket' seat version that is mounted to the bottom of the canoe. I cannot, for the life of me, figure out a suitable way to get a backrest installed with it. Best bet I've found would involve a Wenonah superseat, or similar, and mount the straps to the rivots in the gunwales. Problem is, I have neither the equipment nor the skill to be attempting re-installation of the rivots in the gunwales assuming I'm lucky enough to get them out.
Hopefully I'm explaining this well enough. If confusion seems common when in the reviews/responses to this, let me know and I'll post one of those things that speaks a thousand words. Thanks for checking this out!
Rather than go to all that effort, I'd opt for the original seat designed for the tractor style seat that Wenonah uses. Although labeled the "super seat" on the Amazon site, the profile looks to be the original design. You can use the "under seat" straps to secure this design to a tractor-style seat if you simply add a buckled nylon strap under the leading edge of the seat.
I've use my seat with this design on my Prism until I completely worn it out.
Another use I've found for this seat is for "in-camp" seating. I take an inexpensive folding Coleman Rambler stool and strap the "super seat" on top and you now have a stool with a padded seat and back rest. (I'm always looking for gear that can be used in multiple ways.) BTW: I typically strap the Coleman inside my canoe on the thwart just behind the Prism tractor seat, with the U-side up and the legs angled slightly forward behind/under the seat. This also provides a bit of back support independent of the "super seat." With a couple of bungee lashings, it rides there perfectly well on portages.
"If you can keep your head when all about you are losing theirs" chances are you missed something. (Inspired by Rudyard Kipling.)
I have been very satisfied using a "Crazy Creek Chair" on top of my Prism tractor seat. Your weight holds it in position but I have a quick release strap on the front and a loosely attached strap rearward that keeps it in place for portaging. Ten seconds and the chair is out of the canoe and ready for other uses. I use a kayak paddle and try to use my torso for paddling. When the going is hard I like to roll up a jacket and place it in the small of my back. Then using the foot brace and drawing in the straps on the chair to pull the lower part of the seat back firmly into my lower back I can freely move my upper torso for maximum power.
I've explained this somewhere before here. For an attachment point for the side support straps on a superseat. I simply wedged a straight Mt Bike handelbar under the front of the seat and hooked the straps around the bar. The bar stays in place , but still allows you to move to seat forward or backward. It works
quote Savage Voyageur: "Just put a crazy creek chair right on top of that seat. Problem solved, added bonus is a pad for more comfort. " I actual tried the CC Canoe chair with not so good results. The shape of the tractor seat doesn't lend itself to well with CC chair.
You wouldn't need to remove any rivets to add a place for a super seat mount. Do you have a drill and a drill bit? A low cost rivet gun will do the trick or you can use a couple 10/32 nuts and bolts (stainless steel preferred) on each side sized to be flush with fitting. Drilling out old rivets may not give you the placement you desire anyway, go ahead and add a few.
Just to add some background, I did need to purchase two pair of fastex buckles to make this work. I replaced the one on the tether which mates to the back of the superseat, in order to mate to the mount up front. If you can get the same mating ones it would be beneficial, but they all do not mate.
If you are interested in the solo yoke backrest let me know.