There are civilian pilots (General Schedule - GS11 -13) who are pilots in the Army and Air National Guard; however, they are what is known as, "Dual Status Technicians". In other words, their employment is contingent upon their ability to hold a drilling billet (fill in the military rank here) in the unit which they are supporting. Therefore, IF you would forego your retirement check, and IF you were able to find a unit to accept you into a commissioned officer slot, and commission you, it could work. But I can't imagine any scenario under which that might happen.
But, on the other hand, If you want to start an airline career (different retirement check), you will be eagerly sought by a regional airline if you get a few easily obtained ratings. After which, you will be very attractive to any number of good airlines. Although you may think that 43 is "old", you'll have enough time to do twenty years at a decent carrier if you get started now. PM me if you want a road map from a guy whose made all the mistakes.