My GMO experience:
30% Psych: Depression, Anxiety, Adjustment Disorders, Personality Disorders, one true psychosis
20% Derm: acne and rashes galore
20%: Ortho: chronic stuff (PFPS, back pain, etc), acute fractures and dislocations
15% Gyn: routine stuff, bleeding, pregnancy
10% IM: DM, HTN, lipids, thyroid, occ rare stuff like IBD, other autoimmune dzs, meningitis
5% Urgent Care: chest pain, belly pain, lacerations, ocular foreign body, GI bleed
What I think you need to do this job right: a primary care residency
What I had: a military IM internship with rotations that included ortho, gyn and psych (but no Derm)
What you should do : Learn to identify and take care of sick. Learn to splint. Learn to do a good gyn exam. Learn to suture. Over-consult while in garrison. If the specialists complain, just point out that the AF in its wisdom has you pretending to be fully trained while taking care of our nation's heroes.
My bias is that you would be best served by an IM internship that provides you with more than the average amount of flexibility/elective time. The military TY years were more rigorous than average but still too easy. The damn trannies still got days off to go out together and play dodgeball.
You can also plug these holes as an MS4. You are going to be a practicing physician very soon so you shouldn't take 4th year off. Do an ENT elective. Get proficient with a slit lamp. Do an acute care ortho elective (they will let you hang with the cast techs who can really teach you to splint in a week). Do Derm. You get good at that stuff as an MS4 and you'll be fine with a medicine internship.