I did it ten years after graduation at the OKC fsdo. They didn't even ask for the letter when they saw that I survived AF UPT and saw the T-1 in my logbook. BE-400/MU-300 types added. Just like you, I waited until my last year in the service to do it all. It worked out just fine for me.
The rules have changed greatly for military competency type ratings in the last decade. Read up on it. It is a little easier than it used to be in some respects and harder in others.