Just before going down, breathe in and push out against the belt and hold it. Hold it all the way up. The first few times you do this your abs and sides will be sore but they will get stronger with time. This is the secret to spinal health.
Also, heavy good mornings for triples while bracing like this will work wonders. Think about this. In the bottom position of the squat, when you have some forward lean, is that not a good morning? If your legs can squat 500, but you cant hold 500 in a leaned forward position what will happen. I have worked the good morning so that I can good morning more than I can squat so I dont ever worry about back stability in the hole.