I'm sure there's some ultra-minimum security prison he can get himself into.

Minimum security prisoner status can get you a mobile home to live in on the prison property, shared with too many other inmates, but not "in" the prison. And the guards mostly don't hassle you, except for regular inspections of the cleanliness of the home and making sure you're always where you're supposed to be when you're supposed to be there.

IDK what we have for rich political mofos, but in no world would Trump be put in what most of us recognize as a prison.