[AustinSchuh]

Looks like my original comment was eaten, trying again.

Not bad. From my experience, I'd recommend making the following changes. Sorry if I come across a bit terse.

Move the flange from the sides of the belly pan to the rail, and make it the full length. That will make your frame stronger. I try my hardest to not break critical flanges like that to keep the strength up.

Make your frame as tall as you can get away with. Again, it will be stronger.

Put another bend on the inside of the front and back rails to make them stronger. I'd also make them at least 1.5", if not 2" deep. Our 2012 chassis has bent front and back rails from impacts, and is beefier than yours.

Lighten your rails more so you can see the belts/chain and get your hands in to fix it.

Not enough rivets on the corners. They will sheer in my experience.

How are you going to replace a belt when it breaks? Between matches?