I've been thinking about that idea myself. Use a "shear pin" of sorts. Shouldn't be hard to do, maybe round out the inside of a hub so it will free wheel, but attach (was thinking weld, but the stock cast won't work) it to... say... the spacer found on durablue's extended axles with a hole for a pin and drill the axle to allow the pin. Get to the riding spot, then slide the pin in and your good to go. Should work.
ive been thinking about that for a long time but never really knew how to solve it. the pin is a good idea but wehat about when you need to do street drags. plus hell, i can easily light up two tires. itd be hard not to scratch even when mildly gassing it.