I’m determining the limits
… or, as I would say: you risk your Duet. The hotter a chip, the faster it fails. Do you really want to determine the limits of the board?
I upgraded all my motor wiring to 22 gauge. I was hopeful, but it didnt help much with the heat on the drivers.
It can’t. That just helps you to pump more amps through the steppers and to dissipate less heat by the wires. The drivers still try to provide 2 amps if you tell them to do so in your config. As @dc42 told you several times in this thread: apply active cooling!
After you’ve done that, check the temperatures of your steppers. As long as these don’t exceed 60°C, you’re safe.