MT,

I have a Kayak compass that I used on a few trips. Mine came with a bungee strap/hook rig so you could mount with the using the deck rigging found on most kayaks.

Since the canoe doesn't have that option, I did a little out of the box rigging and just secured it across my day pack and propped the day pack against my portage packs.

I checked the heading against my Brunton Orienteering compass to make sure nothing in packs was affecting the kayak compass.

 I liked it a lot. I didn't see it bobbing around, it's dampened and obviously your just occasionally checking it and lining  up on a distant point to reach and re-orient yourself.

On big plus in my book, is that unlike a hand held compass or GPS, you don't have to stop paddling to check your course.

Depending on conditions, especially solo, stopping forward momentum can be a real bad thing ;D

PS, Good luck on your medical problem. Getting the extra weight off will serve you well, whatever choice you make.