Well we did it today. The run was 121’ of 8-gauge wire, with another 2 feet to run between the plugs. Seeing as how I had a 125 foot spool of wire, I cut it pretty close!
It is not easy, but not impossible to feed in and jumper the 8-gauge between two hospital plugs in the dual wall box, but using the deep box, we managed.
I also ran RCA panels with six leads from the inside to the outside of the entertainment cabinet to allow me to access various aspects of the system from outside of the cabinet. For example, this would let me bi-amp if I so desired.
Just need to mud a couple slots in the drywall and paint now.