[usual preach]
The idea to use the player's belly (or balls) for shielding is life-threatening nonsense in the first place.
If you do a complete shielding job on the cavity and all cables to pickups, switch and plugs you will have no difference in hum between touching the strings or not (with no ground wire). But there will be a huge difference in life expectancy if you ever play with an amp broken the wrong way.
I would see this as an opportunity, not a problem.