I stayed at a hotel in pattaya and they claimed they could not give me a TM30. They gave me a letter which I took to immigration. Immigration checked on their computer that the hotel had registered me and they gave me a piece of paper for my passport to show I was registered.
An onward ticket may be required by your departure airline. I know Delta/Korean requires one. As for the TM 30 as others have said, by Thai law your wife is supposed to submit one when you go to her house.
I have been told that we cannot use tricare to meet the OA visa requirement. So I opted for an O visa. I can still use Tricare. A few hospitals accept it but generally you pay out of pocket and submit for reimbursement.
While Wise fees seem high, also look at the exchange rate they offer. I compared Wise to Western Union (95 cent fee) and WIse has beat out banks & WU every time.