that's why i invested in one of these, links the 2 pedals together with hardened pins. several land rovers use them (old ones with the canvas tops) and they noticed a severe drop it thefts on the forums by the ones having one.
Disklok is all fun but it doesn't work on my wooden nardi (they can just stick a bar in the rear adapter and are able to steer it.
But again if they really want it they'll take it one way or another.