[Woolly]

Your way of going about it is interesting, though the way I'd achieve what you're talking about its putting what amounts to putting a deployable jack just behind the corners of the frame with plaction tread on the plates that contact the ground. The thought being that you want to get as much of your robot's weight on the highest-traction surface you can.
That and it would just be useful to have built-in jacks on the robot for testing autonomous and such (just have a DIO on the driver-station determine whether the jacks are engaged or not during autonomous)

It's definitely something that we've even thrown around, and worth testing.