I would go to your local Thai Area, if there's any Thai's in your town they is bound to be a Thai supermarket or provision store. They probably have registered Thai Sim Cards they will sell you, I use DTAC so I know how it works, for the first 2 or 3 recharges it adds progressively longer validity times, till you end up with about 12 months each recharge, you can recharge via their website but you need the phone to be active to receive the Passcode via SMS to log into your account.
I've owned 2 Condo's (made into one large 225 squM one) that I use to visit for 4 or 5 days a month every month plus at least 2 x 2 week or more visits a year. It was my Circuit Breaker for the pressure of working long days in Singapore. I've looked at all the various visas, but 2 weeks in Quarantine tough to do, plus the totally confusing/costly insurance.
All good in terms of Covid, pretty much out of the community. Maybe 1 case in past week, like everywhere else still returning cases from overseas. Pretty much free movement but masks worn everywhere even in my own office. Social distancing enforced & limits on meeting/dining of 5 people. Really crowded in many places as locals return & no travel means quiet places aren't so quiet.