Access to the driver's side rear bolt is compromised, but possible. I approached it from the inside and tolerated 1/8 turn at a time. After that marathon, others here noted that you can come in from the top if you have the right length extension for the socket.
I lowered the subframe both rear corners about as far as the big bolts would back out, i.e. about 2". It would not lower all the way even though there was enough slack in the bolts. Used the pry bar on a jack to push it down a bit more. Only then I was able to loosen the rear bolt with a 3/8" drive ratchet, then use a ratchet wrench from the inside of the subrame like Tachoma Pilot suggested. There was no way I would be able to loosen the rear bolt w/o lowering the subrame.