Yes the pistol lowers may be the way to go. If you plan on bolting or screwing an adaptor in remember that you can't go in through the receiver bolt area. The plastic part of the bolt assembly banks on the flat of the lower adjacent to the buffer tube. Unless you counter sink the bolt or screw it will interfere with the bolt.

I thought of doing this a while back. Was going to make an adaptor that would fit in the buffer tubes place. Then make the opposite end fit the removed tube so I could put it back on. A folding stock would be cool.