Someone else shared a link to "saddlebags" for bench-seats for sale at the BWC online catalog -- they look good, too. I have boats like that, so will take a look at them for suspending pouches from those kinds of seats.
We have tried a variety of thwart bags, underseat bags and side seat bags. I will now complain about almost all of them.
The thwart bags, if hung from a thwart close enough to reach into, dangled against my ankles and were in the way of getting my feet in and out. Underseat bags were in the way of kneeling and, worse, required a blind grab and tactile grope around for what I was looking for. Side seat bags were somewhat less of a kneeling issue, but were hard to peer into, and like the underseat bags had zippers.
Anything with a zipper was problematic for me, in part because zippers can eventually suffer from grit and saltwater, but also because most required two hands to open, one to hold the bag, one to pull the zipper. Anything with a waterproof zipper definitely needs two hands.
One style bag that did work well was a thwart bag, retrofitted to hang from the inwale, kinda like your tool belt.
My wife still uses an “Otter Pocket” bag, which is basically a nylon envelop (without the fold over flap) hung via cord between deck hooks on the inwale. An even better version was a “NutSack”, a DIY thing made by a friend, much the same design but using bungee instead of cord, so it was easier to stretch open and look into, and a fine weave mesh material instead of nylon, so it better drains water (the OtterPocket after a hard rain became a mini-swimming pool, and I stuck a couple drainage grommets in the bottom).
My favorite catch all bag for canoe use is the simplest and least expensive, a small soft side cooler. There are hundreds of soft side cooler designs and dimensions, so lots of personal choice. The best of those I have found have been:
A 6-pack sized soft side cooler that has a hard plastic liner and plastic lid with lip inside the fabric skin. The lid has no zipper, but the lipped lid closes snuggly via a Velcro tab. It only takes one hand to open, I can see inside at what I am looking for, it is waterproof (at least in terms of rain or bilgewater), it floats well, it has an outside mesh pocket and a carry strap. Since it holds my “essentials” it is easy to set beside my chair in camp (the OtterPocket or NutSack are less handy in camp use).
The other soft side cooler has become my usual “essentials bag”. That one is a long narrow cooler, 16” long x 6 wide x 6 tall, with an opening at each end. It was designed to hold 12 cans, loaded from one end and retrieved from the other.
The 6 x 6 dimension is really convenient; it fits under the seat or between my feet and legs and is easy to pull towards me to extract whatever I want from either end. It is slender enough that it works even in narrow boats, and in the decked canoes between the foot pedals. I love the design of that slender cooler and have been looking for another one (Polar Jacket 12-can Dispenser) for years.
Another simple catch all is the DougD favorite for use with bench seats; some mesh netting suspended pouch-like between the side of the seat frame and hull.
None of those favorites, Otter Pocket, NutSack, soft side cooler or seat side mesh pouch, is waterproof. Those things I really need to keep absolutely waterproofed go in a small dry bag or Pelican box, or go in a tiny waterproof bag inside the soft side cooler.
Back to the solo canoe “table”; that rigid platform, in combination with a simple soft side cooler, would seem the best of both worlds. I am intrigued by the fishing lure aspect, having a little strip of minicel affixed in which to embed hooks when changing lures or rigs. That naked hook bit always bothered me when fishing from a canoe.