Warning: my drawing is crap but it probably an accurate depiction for why all the threads are busted.

I have an aluminum undertray for the ralliart. It bolts up between a chassis brace and the frame. Unfortunately, all 3 bolts that hold the brace/tray seem to have stripped their threads. They all turn wonderfully freely and never release. This is blocking me from servicing the transmission and transfer case. Anyone have any sweet tips on getting these things unstuck using my driveway and charisma? Happy to drive to harbor freight and pick up an extra tool or two if it will help.

I’d like to avoid drilling them out if possible because it’s a really awkward position under the car.