So I've modelled and printed an 80 x 80mm area test print. The thumb Tetrinsic is 4.8mm higher than the finger Tetrinsics.

I might as well get the bad news out of the way. When using all 4 finger Tetrinsics, my thumb feels like it has no space and Finger5 is very close to rubbing on the edge of the Thumb Tetrinsic on the other side. This diagram I made in PowerPoint helps illustrate this:

Tetent is already too long to fit in the bottom section of Teti, and adding another 20mm to the bounding box in X and Y does not help!

The good news is that 4-fingers / 3-fingers-and-thumb configurations line up without anything feeling off-centered or misaligned. It also seems like I'd be able to get away with all 5 Tetrinsics if I position Tetent at an angle:

If anything... it feels like the actual strat. Still need a tiny bit more thumb space though...