Help!! 02 Neon Subframe bolt spinning

I am trying to replace the control arm bushings on an 02 Neon. On the rear control arm bolt the nut is spinning in the frame. What is the least painful way to fix this?

Cut some slots in the frame rail (on side,outer side) in the shape of a u and bend it up. Then you can put a wrench on nut (will probably need to be heated) and get bolt out. When done bend peice back down and weld it up. Happens quite often.

Use a die grinder or dremel with a cut off wheel and make a window, you may be able to use the cut off wheel to cut the bolt off as well.
Be sure to reweld the repair.