Taller=longer back=higher center of gravity=more back discomfort in squatting.

Answer=build up the back and the stabilizer muscles like chinpeace suggested. The torso muscles come into play here. In other words, some
of the back pain you experience could be the result of weak abdominal
stabilizers.

Squats, deadlifts, etc. will help fix this. Also direct torso, ab work. The higher frequency is gonna help here, too.

In addressing these problems, as long as there is really no injury (and to
some extent even if there is) I would stay away from a lifting belt. That
abdominal cincture effect replaces what the muscles are supposed to be
doing for themselves and so will be a detriment, not and aid to alleviating
the weaknesses.

IMO, if you avoid working on squats, you will really be handicapping yourself. You really should try your best to have squats in your routine.