Just mount the esc over the rear shocks - Just use a small square of plastic - a couple of spacers and longer screws for the shocks.
One thing to watch though is the rear arms - The teckno mount puts the motor a long way back are you sure there is no interference of the motor and arms?
Ok I have mounted the MMM over the rear shocks but now the MMM is sitting too high, it is above the body mounts, I have mounted the MMM as low as I could, and raised the mounts as high as they would go. Any suggestions?