[Deke]

It looks like a very nice design!

Two comments on the gearbox plates:
-If machining, you will need some internal fillets on the corners for the mill. Even if you are using a water jet, fillets will reduce the Kt of the stress concentrations in the plates.
-The thickness around the bearings may need to be increased for press fit, otherwise the press load could tear the metal/material.

I really like the gearbox incorporation into center 4 wheels. The Enginerds (2337) did a similar approach last year and had a very robust drivetrain.