Not an answer to the OPs question but related - I had my custom road fix gear made with horizontal dropouts designed to allow any cog from 12 to 24 to be used without messing with the chain. (I do have to use a 1/2 link with one of my chainrings.) The dropout is cut from 1/4" plate. Think a conventional horizontal dropout lengthened considerably more than the old long Campagnolo dropouts of the early '70s. I think the hub can move around 1 3/4" but I would have to go out and look. It has less incline than a standard dropout so the height of the bike doesn't change much. The final slot, installed, is at an angle of 11 degrees. This allows the brake pads to stay on a Velocity Aero rim. Finally the opening to the dropout is from below at the very front so you slide the wheel forward, then down to remove. Install is just like any vertical drop. You then pull back to set chain slack.

Other touches: it is threaded for a typical fender bolt slightly above the slot. I run a nutted pan head bolt in from the inside to act as a chain peg. Really handy when flipping a fix-fix wheel. And I have the common adjusting screws so I and replace the wheel exactly and fast when I am not chaining cogs. Nice but I have rarely used the feature. (Now I really love the same on my workhorse fix gear.)

These dropouts make riding hills and frequently flipping the wheel easy, fun and fast! Between that and a chain whip I made that straps to the top tube, I can ride monumentally hilly fix gear rides as a 60+ yo and have a blast. When I am in practice, 2 minutes to flip a wheel, 5 to change cogs. (My epic Crater Lake ride - 7 flips, 2 cog changes. 10,000 feet, 98 miles. Couldn't have happened in one gear, Not this body at 59 years old.)

Ben