Thanks for this, Dan. The Ovo-shifter is intriguing--I could imagine mounting it close to the brake lever on my rando bars, or possibly on an auxiliary bar mount a little further inboard. The more vertical mounting in the video made me wonder about rain and airborne crud finding its way into the ratcheting mechanism. Trust/hope that the mounting will have shims to accommodate bars of different diameters.
In a hardly-related vein, I was interested to learn of your nautical background! I've sailed across a few oceans, back in the day, but on big ships. You might enjoy a very good read, written by Nicholas Coghlan, a former colleague of my wife -- Winter in Fireland: A Patagonian Sailing Adventure. It's his account of sailing from Cape Town to Puerto Montt in Chile, including wintering over in Puerto Williams in the Beagle Channel on the opposite shore from Ushuaia. (I don't do watery stuff at such levels, though "messing about in boats" is good fun (see below).
J.