Do them in the reverse its far better for your back and less likely for injury. Infact it takes all my lower back out if done correctly. I would go with the same stance as with normal BB squats around shoulder width apart with your feet pointing out. When your feet point out it activates your glutes more and if you visualise trying to twist your feet outwards this will tense your glutes and put your body inline and your spine straight. Put your hands on the top of the pads near your delts and pull down with your elbows so it locks your back up again this will tense your back and support your spine. Brace by using the diaphragm and breath through your stomach and not chest. Your spine upper and lower is protected and the power from this position is amazing, At the top of every rep go through those 3 positioning and lockin for the lift, it will only take the same time as one deep breath in once you get use to it. Stick your arse out and keep your back straight no under or over extension but you should be fine if you have done the above.. Also make sure your knees don't go over your feet, make sure your feet are in enough so this doesn't happen.