Lessen made some good points. Plus the amount of mod needed may be a pain in the rear.
I just completed a hidden body mount modification on my HPI Sprint 2 drifter that uses neodymium magnets screwed into the body posts & washers epoxied to the underside of the body. The actual modification to the posts was minimal, just cutting down the height of the main posts & attaching the magnets to adjustable post toppers. It looks very clean and the magnet strength is more than enough to lift the car by the body and bounce it around without coming off. By epoxying some drywall tape to the underside of the body & then epoxying the washer on top the tape it spreads out the pull force so you don't get any paint lifting/pull when removing the body from the magnets.
I'll try to get some pics up today in my Members Projects thread on it when I get home from work.