Thanks my friend.
So, the 30-day visa expires at the end of March. As long as I arrive in Cambodia before that time, it will last 30 days from the date of arrival. Ironically the immigration department is located conveniently across the street from the airport, the place where visa agents drop off their packets to renew/start the one-year visa.
There have been a few cases of people successfully arranging their own work visas, but you have to have all your ducks in a row, the Cambodian authorities will not tell you if your paperwork is correct, and they won't answer any questions, thus king of encouraging you to use "visa fixers". I think I now know the process well enough that we could perhaps do it ourselves, fingers crossed.
Funny, I just received my Crypto.com ATM card. The only reason I haven't withdrawn any crypto via US channels is that I don't know much about taxes, so I don't want to fool with it. I think Binance P2P into my Cambodian wife's bank account, then withdraw via ATM will be a tax-free way to access our crypto. My Crypto.com card can definitely be my all-else-fails solution though.