My wife will not go out with me without them, she HAS TO have some back support. And with small kids they increase security immensly. The rests also make for very leisurely sailing when winds are lighter (most common on this little lake).
My wife always wants back support also, and I liked Corey's seat design, but it doesn't exactly work for a Club Wave. So I started keeping an eye on stadium seats at Wal-Mart, etc... that could be adapted to the task. I found one in the close-out aisle at Walgreen's called a "My-Pod" for $7.95, and thought I'd give it a try.
It's kind of an oval shape when laid flat, then the back bends up to leave a round seat. It has a metal frame, with a ratchet hinge, and is very sturdy. I thought it would need a tether to keep it from rocking backwards (Wife overboard!
), but the design makes it stable. She loves it; and without the tether, she can move it around, sit on the tramp (there are no corners or sharp edges), sit facing forward, sit up front facing backwards (to make faces at me
), whatever. And when you're not using it, it folds flat, about 1" thick, for easy storage.
I googled My Pod Beach Chair, and found it through lots of sources, but prices all over the place, from $15 to $50.
Not a commercial, but a recommendation if you need back support.