won't work
I have heard ( no first hand experience) of success with this on Cruise Ships from several people.
As far as in person at A.C. B&M cainos, not only will cage charge you an exhorbinant fee (via a third party vendor that pays casino a commission), but your C.C. will treat as a cash advance and offer no grace period on interest charges.
When in Laos, I was able to "charge" U.S. dollars at a local travel agency to a mileage based card for a 6% commission.
i.e. , I signed for $318 and recieved $300 USD, not local currency,
I did this because plastic and even local currency payments are "penalized" by vendors and there is a strong partiality for US Dollars ( heaven forbid there is a crease or wrinkle in the bill).
I did not bring enough cash.
so I did this but I cringed at the 6% fee.
back to your original question, I think that any manner of "free" miles is not achievable in any meaningful critical mass.
If you want to sweat out deliver issues and run to the bank do a search of "US MINT" this may get you up to 20,000 "free" miles. I don't feel its worth the hassle.
Another manner, -- that I personally consider unethical is the "costco" loophole.