I FINALLY got around to reading this, having bookmarked it when you first posted and then suddenly gotten very busy, and this is fantastic! The defensive, champion-y direction you took it in is really interesting and a pretty unexplored design space in terms of first-party material, with champion and, I guess, arguably monk being the only real examples. I wish I'd been present in this thread while discussion was going on bc there's some real refinement here.
I am curious, though, how concrete your plans to put this up on PFInfinite are. The reason I ask is because I'm currently working on a travel- and road-themed Infinite product, which, obviously, this design concept is perfect for, and I was considering a post-GnG update of my original version of the Drifter for that book. I'm planning on taking it in a pretty different direction than you did (focusing more on the big-damage elements as a midrange striker class a la the ranger), but its still the same thematic territory.
I don't want to just step on your toes, since you've put in the time on this, so I was curious how likely it is that you'll put this up on infinite and, if it is likely, whether you'd mind a similar design in my product.
(I would've just PM'd, but I couldn't find the PM button on your profile--I'm guessing its a bug because I couldn't find said button on the profile of anyone else here when I checked, and it seems unlikely that everyone on this thread has me blocked lol)