[Kevin Ainsworth]

Nice design. You even have the weight of the robot pinning the steering bearing into the wheel module and the mounting plate. Others have hung the weight of the robot off the screws on the edge of the bearing which is a no-no. I don't like relying on screws that aren't seated fully like the ones you have on the main steering bearing but since you aren't holding the weight of the robot off them it should be fine. I would use stripper bolts or machined tabs but with a little loc-tite the screws shouldn't be an issue. Plus they are very close to the main plate and if one came loose it could lockup your steering for a match or burn out a steering motor.

The answer to your problem of mounting the CIM to the main plate is easy.
Flange the motor/bearing adapter (plate between the CIM and steering bearing), and make that flange larger than the hole in the main plate, assemble the whole steering module and slide the whole thing up into the plate until the flange contacts the main plate. Then you can clamp on the minor OD of the adapter instead of the CIM or bolt the flange to the main plate (my preference). If I am seeing everything correctly you should be fine. It will add a 1/4" to the overall height but that shouldn't be an issue.

One thing we've found is when the steering gear is smaller in diameter like this, the backlash in the steering gear to steering gearbox and within the Versa Gearbox, you get a decent amount of steering backlash. We are going to belt steering over gears due to this. Modifying a steering gear is simpler and easier, but for autonomous routines a low backlash steering helps a lot.

Awesome new evolution of the type of co-axial setup Aren started a couple of years back where the bevel gear is on the wheel axle. Though it looks like you're using a tiny 1/2" x 2" wheel, that could also be part of the compact look. Our 2015 1"x3.25" wheels looked laughably small.