It's awkward to use a single blade paddle if you are sitting on the near bottom. If you can get a pedestal mounted seat to raise you up a few inches, which may require some reinforcement, you can easily use a single blade. I didn't bother trying to modify my Hornbeck, but bought a Placidboat Rapidfire with a high rail mounted seat. I paddle it single blade all the time.
There are several dichotomies in pack canoes, the most obvious between minimalist hulls verse more rugged and comfortably outfitted trippers. Another split is between tumblehomed verse flare sided cross sections. As of this note, Mad River's Serenade, Old Town's Next, Placid entire line and Swift's Kee 14 are the only tumblehomes hulls. Narrower, tumblehomed rails greatly enhance single stick paddling for kneelers and those sitting high, and are almost a requirement from a low seat. We've found a 46-47 in bent paddle works best, but a straight blade maneuvers better in twisty streams. A smaller blade helps too. Marc Ornstein makes a top end product near $300, Fox has a very workable pack canoe paddle around $100.
The single blade is a requirement in the Pine Barrens and on little, alder choked streams everywhere,