Forget the freeze. Use a hair dryer. My experience is that freeze doesn't work on older games. The pop rings are very hard to get up. You may loose some paint in the process. Use a plastic razor blade and some Goo Gone and heat. Take your time.

I do primarily early SS Bally and Sterns. I've tried freeze on every Mylar removal. So far it's freeze 0 and hair dryer 8.

Heat guns scare me. I usually use a latex glove when using the hair dryer because my fingers get too hot.

This may be too late, but after looking at your pics you may want to avoid removing Mylar in areas where there is planking. I'm working on a SBM with factory installed Mylar. One panel of the PF was suffering from planking outside and underneath the Mylar. The raised gain caused the ink and finish to delaminate. In this situation there is no removable method that is non-destructive:

SBM planking.jpg
sad trombone.jpg