Apparently the need is not THAT high if you exclude people over 60. I know I read before you not make the rules but I certainly would consider to talk to management to change.
Mmm, I must admit I never read that with a multi entry Tourist visa you still need the '3 proves' (20k฿ (or equivalent money) cash, Prove of stay and onwards ticket within 60 days out of Thailand) with a border hop/bounce. In my thoughts it would be a bit strang with that visa. Visa exempt is a different story. But.....y'll never know. Maybe better ask at the Thai Visa Advice group (without 'and everything else'). There are some very knowledgeable people.
If you come back to Thailand just a couple of days before the visa expires, you get (the last) 60 days of stay again. And this you can extend again for 30 days at the imm. office.
Just mention; think y'r embassy still hands out income statements ! Ofcourse after exchange rate, it has to be more than 65k฿ per month. Only need 800k฿ for initial Non imm. O incountry (when making this IN Thailand). Not always if e.g. you do it in another country in a Thai imm. office. For year extensions you can use these income statements. But maybe you know this already 🤷♂️
No live experience with this trip but should be possible ofcourse with visa exempt. Only thing I would do is getting the three things they can ask; have 20,000฿ or equivalent in CASH, Address/hotel booking and onward ticket that you leave Thailand within 60 days. In this case a ticket for the boat/ferry to go back 🤷♂️.