Putting it bluntly: you can’t.

If it’s to the point of requiring surgery - although what is deemed as surgery requiring varies from place to place - there is no work aroud, no coping mechanisms.

That narrow of a time window, on my own personal experience, tells your condition is pretty serious.

Does your jaw clicks when you eat or talk?

Maybe some physical therapy can ease you a bit. A good therapist may even work on the information you may give them, from what you remember from when you were diagnosed.

Ball gags, or anything that forces your jaw open, are off the table. I’m making some guess work here but I think you have an higher than average risk of getting your jaw locked if you force it. I can’t describe to you how painful that is and how even more painful it is to have it reset.

I respect your fantasy/fetish/kink but you are better off putting this one to rest.

Give what you can and whoever complains about it can go fuck themselves. And reading what you’ve posted, you grant a great joy ride for a lot of lucky dudes.

I sincerely wish you can prove all of my worst expectations wrong, without endangering yourself in the process. And hope to read about if it ever happens.

Stay strong.