We live here full time and when we relocated we researched and agonized over this. We concluded that regular medical care ( colds, flu, broken bones etc) is VERY inexpensive here. I came down with something and went to San Jose clinic and was seen, had a full blood work up, and got meds for a total of $29.
For serious stuff they will stabilize you and send you to either Hermosillo or the States for treatment and the distance is close to the same. In the end we couldn’t see any value in getting a policy beyond that we already had which like yours was Medicare and a supplement.