From photos, the so-called "field hospitals" look barely better than jail, and getting a COVID bed in a true hospital is increasingly difficult, perhaps impossible in Bangkok.

 

Is there a list online yet of government-approved hospitels in BKK?

no, thai prisons look different from field hospitals. 

Foreigners are rather put in better conditions. On phuket there were put into private rooms at student dormitory, above the large student meeting hall with hundred beds, and it was also free.

I would rather try to convince authorities to stay home and even pay penalty for not coming to the field hospital, or even hospitel.

Probably foreigners will be charged around tens of thousands for hospitel, more than the cheapest ASQ hotels for flying in.

But advantage of being there is that in case of symptoms, you will be transferred to hospital, given check ups, medicines. 

If you become symptomatic at home, first they will try to find space in the field hospital, where there is some basic medical care

No idea how accurate or up to date this is, and you'll need a translator, but this could give you an idea.

 

http://hsscovid.com/files/hospitel-bkk05-05-63.pdf