I’d apply for a tourist visa before you go and you get 60 days as mentioned above. That way you don’t have to mess around at the local immigration office while you’re here. Visa application is all online nowadays and don’t even need to send your passport to the embassy anymore.
You could get insurance with Safety Wing.. it’s pay monthly @ 42 USD per month and you get a confirmation letter 15 mins after buying. Cancel any time. The confirmation says it’s valid for 1 year from the date you purchase. I’ve just used it myself for the Thailand Pass.