Another hard one. I'm looking into this, but it seems you have to pay for health insurance at 'home' (planet earth?!?!) and then pay also for travel insurance to get to 'home' wherever that is. hmmm.
As you may have guessed, I don't have a home, call it campervania.
I eventually got international European insurance for 'expats' with IMG. I'm hoping that if I'm in a car crash, I'll be taken care of. See details here