1) April is still a "long time" , nobody knows what the rules will be by then.
2) If I were in your case, I wouldn't risk to have gf come stay together on that 5th day. Because if you would test positive, she could be in trouble because she was in high risk close contact.
If you test positive and she doesn't stay with you that day, she can just do some ATK self testing and self isolate if necessary instead of risking being held hostage by the hotel/ hospital and paying too much for whatever forced quarantaine and unnecessary medicines.
I'm not saying there are never problems (depending on wrong insurance or other problems), but it is definitely possible to have direct billing if you have the right insurance.
In my view :
First of all, choose the right insurance.
Second : make sure you know the right steps and the correct communication channels before you need it, write it down on your insurance paper. Be prepared. So you don't lose time and avoid miscommunication problems at the moment you are too sick to deal with anything.
Third : get your insurance through a good local agent. When there is a problem, the help of your agent will maken a huge difference clearing up any mess.
If they have the right insurance, then people traveling on holiday don't have to pay first and then claim after from the insurance if they have to stay in a hospital. Hospital will bill directly with the insurance.
If you have had other experiences, I believe you. But that means you had a different insurance.
I can confirm this from personal experience. Yearly extension of stay based on retirement non-o visa I have never needed health insurance. It was never a requirement. Not needed to apply and get the yearly extension. BUT it is needed to (re-)enter Thailand (to get the Thailand Pass).
baht each month. Can not be a bit less some months because you have a bit more other months.
If you did the
*****
0 baht deposit method, then you can use this deposit for all the coming years without worrying about the monthly deposits. (there are specific rules on when and how much your bank account can or can not go under the
*****
0 baht - be careful and I'd advise a dedicated account for this deposit.)
OR you can do a combination of the 2 methods : for instance