I and my friends have a couple of Trail Blaze builds.
It has a standard BSA 68mm BB and a 142 thru axle rear O.L.D., so when using wide tire (>2.0), the chain may interfere with it. One of solutions is to consider a wider crank.
And regarding the cassette, I don't think 50t will fit, because you can only use short or middle cage RD.
That's sharp! I love slate blues. Bonus points for the Thudbuster post!
Even a cheap Tourney GS (mid) length cage provides 43T capacity, which would handle 11-50, however the slope the parallel linkage moves on is not steep enough for above 34-36T low. Ron's video shows it works with his chosen RD, as long as you are OK with the cage extending below the rim in the middle gears, meaning if the tire flats at that time, the cage is gonna drag on the ground.
EDIT: I have one question about this frame design (and Bike Friday), and I'm gonna post a pic of my bike to help clarify.
The handlepost extends straight up on the steer tube axis, then is capped with a horizontal stem. On my bike, the handlepost is canted forward, to extend directly to the handlebars. The comparative steering geometry is similar. My question is, with the handlepost coming straight up for a horizontal stem, is there any knee striking when climbing standing? My bike with the forward canted post, plenty of clearance, when I put a small, thin handlebar bag on the back of the handlebars, I was hitting it with my knees when standing climbing. Again, for comparison, my bike:
I LIKE the idea of a horizontal stem on top, it allows the option of a suspension stem. But clearance there is critical, I rock the bike laterally when I climb.