most people dont want to hear the truth, but if your back is hurting from going heavy, you need to lighten up a bit and allow your back to catch up. the problem with hacks are exactly what you described, you become imbalanced. the only way your back is going to catch up is to allow it to catch up. i hear people on here wanting to continue overloading a bodypart with a nice stable exercise, and they'll isolate their weak point. all that does is increase the gap, and they never catch up. lighten your load on squats, allow your back to build up some strength to handle those workouts. you can do some specific work for it too, to help it along, but in the meantime if you really want to do regular squats for the overall benefit (legs, glutes, low back, overall body conditioning) then take a couple steps back and build up from there.
Just my opinion.