Well since I replaced two thirds of my running with the arc trainer my hip dysfunction and mobility is quickly becoming a thing of the past. I decided to try squatting on a 21.5"W x 11.5"H box of which I could never get going because I was just so tight it took forever to get warmed up, my form sucked and my hips would be wrecked for days. Well now I discovered I can hit that box relatively easy and my form is way better so I'm reseting and building off of this set up. I'm doing five to eight sets off this box and then finishing with a few sets of narrow ATG squats instead of unilateral work.
I use 116lbs of chain set to barely touch the ground when I stand and this has been a tremendous help getting my mobility better in the hole and allowing me to use some decent resistance still when out of the hole.