With those settings I would use 10. But I don’t think you fully use the battery amps. I bet you don’t hit 40mph on the kick tail and cruse there much? (very simplified - battery amps is top speed torque) put your max battery amps to +45a and 12 should be fine. You can push the boundaries a little because the actual draw isn’t continuous but that has already been partially taken into account by the ampacity on the current ratings chart @b264 compiled.
This puts you solidly past the red for 12 ( think of red as time to stop). With 45a and two esc makes 90 total battery amps. You CAN still run this but you will get hot if you stay in the maximum output of your build for long.
12awg at 45motor amps: ok to burst around top speed but not stay for long.
10awg at 45 motor amps: ok to cruse at top speed but not stay forever, cooling breaks after hard rides
12awg at 65 motor amps: burst could start causing problems, thoroughly inspect when forced to top out. Danger. Do not imho. This can start to hit solder temps and make the meat crayons
10awg at 65 motor amps: bursts at top speed but not long sessions. This is why high amp controllers have dual 10 feeds instead of one shared or people run dual singles.
These are my suggestions based off my opinions and my acceptable risk levels. I also think you will probably be happy at 40 motor amps and only notice a difference when you punch it at top speed. Maybe more noticeable at 12s but i feel plenty torquey at 12s 50a and run 10awg