Sorry if my earlier comment came off as rude. I definitely jumped to conclusions about not squatting because like BI said - it's just a belt squat but it costs more - it came off like a greenhorn question.
You could try more of a powerlifter style squat like POB said, high bar and upright takes the strain out of the back.
Or, if you have to just belt squat, use a dip belt or heavy powerlifting belt and just hang some weight. Stand on boxes or benches.