[AustinSchuh]

This frame looks similar to 971's 2013 drive base. We just released CAD of that frame. Take a look and see if it gives you any ideas. It has treated us very well, so you are off to a good start.

Off the top of my head, your front and back frame rails aren't beefy enough. Make the top flange like 1.5 - 2" long, and add a bend off the back of it for strength.

Any reason why you didn't leave the wheel cutouts as a hole with metal all around it rather than cutting it out to the edge like you did? It will be stronger, especially in the corners.

I like to leave some holes in the top of the frame rail so I can see things like tread wear, and belt (or gear in this case) health.