As far as permissive goes, three main points if you want to give it a whirl:

1) It is best to link the permissive right into your terminal leave.

2) DO NOT sell leave back. When you do, you're missing out of BAH and all that. I know. I know. That last project needs to be done... BL, the mil is going to do just fine without your services. Putting out your last TRP report is not going to save humanity. Focus on the needs of your family. Use that money for your transition if you can capture it.

3) Last, and most importantly. Your CC needs to read into and down with your plan. A quick note here. He cares about his problems...not yours--you are leaving. Present your plan and be able to mitigate training and backfill concerns. If you do, the boss will be a lot more amenable to giving to the flexibility to link up permissive and leave.

I was successfully able to do this when I retired. Good luck.