Good Morning
First thank you for your service. I too am retired Military and have MediCare and TriCare coverage. It is true that TriCare will cover your medical expenses outside the US, whereas MediCare will not (btw not suggesting you are over 65
). Consider two things; one, transportation is often the bigger headache in a medical emergency, and while TriCare will cover it, it may be difficult and require cash payment up front. With private insurance there would be little conversation about transportation. And two, look at USAA travel insurance, it is based on the cost of the trip. Usually the only cost is Air Fare so insurance can be as little as $80. Well worth the cost.
We were with a young lady two years ago on the CF and she contracted the "pilgrim flu" and became quite dehydrated and spent a night in the hospital. The care was quick and very good. No delays, no questions. Don't worry.
Buen Camino
Bob