Don‘t you have health insurance in your home country? Normally you can add a travel insurance for those 3 months with the same insurance you already have.
I‘m doing my „own“ TM30. I just asked my landlady to give me all the copies of her ID and tabien baan and everything needed to upload and registered the address with a new login account which I use. She was very happy and very willing to make me do the whole TM30 thing as a tenant, so she doesn‘t have to do it everytime I return from a trip from another province, which is several times in a month as I travel a lot. The only reason I always need a new TM30 is because I do the 90 days filing online. And then its important that the addresses in the system match orherwise you get rejected. I didn‘t know first and found out when I tried to do online 90 days and was rejected because the online immigration showed that my address was in another province where I was in a hotel for 2 nights.