Since this is target panic, you won't get too much out of blank bale work. You need a target so that you can desensitize yourself to shooting at it.

Start with aiming without shooting. The main thing to work on is to get your pin on the target as quickly as possible. Drawing and then coming down on the target is not the way to avoid freezing. You need to get your pin on the target as soon as possible. Hold it fora couple of seconds and then let down.

After you have done that several hundred times and are getting on target quickly and subconsciously, then get close enough to the target that you know that you won't miss. If that's 3 yards, that's no problem.Continue close to the target until you are sure you are not freezing. Then gradually move back in two or three yard increments. If the freezing shows up at any point, immediately go back to the close target and start over.
Mix in aiming and let down, it will help.

The key is to train yourself to get on target as soon as you reach full draw.

Also, be sure to rehearse your shot sequence on every shot. There is the theory that target panic is caused by shooting your shot sequence out of order. Either a premature hold or a premature release. I don't know enough psycology to confirm this, but I know from personal experience that shooting close to the target and working on shot sequence works.

Good luck,
Allen