Just use 2 individual accounts. You can easily move money between then to balance out your spending. Just ensure you stay with the minimum balances and/or shoe the 65k foreign deposits every month.
Why do you want a tourist visa if you're from Florida? Just show up and get your 60 day exempt. If it changes back to 30, then maybe a tourist visa will help your timing if you're planning to stay longer than 60 days in one stretch.
DTV is only good for 6 months stretches, retirement is indefinite stay. DTV is relatively new. Expect some changes in the coming years as they evaluate how is being used. It is still a tourist visa.
nor does non-o require medical certificate, insurance or criminal background check. Unless there is a compelling reason he would be far better off applying for a non-o from home country. Less hassle and less documentation required.