I would look into each country you plan to pass through and find out what's up. I know at least some provide FREE medical coverage, (even for foreigners)

But critics will say (this varies country to country) it's crap and places you'd end up in are not good. In most countries those with money go to "private" clinics where the best (mostly US trained) doctors may be found.

I know for at least some of those clinics you pay CASH. It's also quite possible your home med insurance will cover your cash outlays as reimbursements. So check with you insurance company before you leave and be sure to save ALL paperwork and receipts for med services received.

Your initial emergency med care may be "hit or miss". But in most countries now there are GOOD private clinics in larger cities. Small villages? Nope.

But your plan to use you Evac insurance to get you back to USA is the BEST ...
if you are well enough to make a 10 hour flight.

I'm with Kaiser in California, and YES they totally cover me in any foreign countries via reimbursement.

There are several Ride Reports on ADV Rider where riders had major surgeries and came out fine! Also read a story or two where some orthopedic procedure was "re-done" once back in USA. Nobody died!

For initial Emergency treatment it will depend where you are ... and really just luck if someone qualified is near you or not.

You will be shocked at just how many really good Doc's are down there ... and how cheap and easy it is to get hold of most medications WAY less than USA prices.