Skegs on canoes?

To me, a skeg drops down out of the stern and is adjustable to help with weathercocking. A rudder pivots at the stern on cables connected to foot pegs and assists in steering. To me what the OP is talking about is a fin - like on a paddle board. If it helps go for it.

Not aware of any canoes with skegs, but there are well-known open-water canoes with rudders - like the Kuger Sea Wind (maybe others) and the Mad River Monarch. Looks like SouthernKevlar has/had a Monarch - he could probably weigh in.

Idiot Savant, have you considered experimenting by pinching the gunnels to decrease the rocker slightly and improve tracking? I know the Echo is slightly under 30 inches at the beam, but some hulls respond better to this technique than others. It is a reversable modification if not successful.

I appreciate tradition and experimentation. If you want to, I say try it. But personally I'd start with reversible modifications. Try hanging something off the back and see how it feels. Of course the dynamics might be different sticking off the back vs placement a foot or two forward of the stren. I feel like somewhere I've seen skegs that attach to kayaks with straps. Or try a sail canoe leeboard or something like it. I wanted a skeg for my rec kayak, and ended up finding some ceiling fan blades that I planned to install like mini canoe leeboards that rotated out of the way. I never got around to it, but tinkering with such contrivances is its own fun for some people. Often there's a reason it's not done, but sometimes you hit on a great solution, and at least you learn in the process. Go for it!