First of all, best user icon. Saw it before, commenting on it now

Second, the intent of supercaps shouldn't be range but batter loading. The limit of regenerative braking is not in the torque of the motor but what you need to do to transform the generated current into chemical energy in a battery. It's not as simple as passing the current through a capacitor, but with supercaps it is. So with the supercaps you can dump extreme currents and either use the energy for taking off or redirect it to the battery.

I demonstrated this in my senior design project at uni and it worked well. Didn't have a load I couldn't absorb with a bunch of the caps. The issue was they're very low voltage, so similar to the li-ion cells you need a lot of them in series to match the system voltage.