In Thailand??? U won't be able to do this even in Sweden or Finland or any other technically advanced nation, you're a foreigner and you have to be able to identify yourself and your status(visa), unless they start to chip people like dogs, u have to carry internationally recognized ID with u at all times...of course most people don;t do that, but it's not technically legal
Just come, buy cheapest insurance possible, if you're lucky u'll test positive on the day five(like many others, what a coincidence), reject to pay for the 'hospitel' and they'll send you to a covid jail, you'll get some cultural insights, adrenaline, unique people, all in one...