The letter the DLT want, is a 'Residence Certificate' which you obtain from Immigration. Prices vary between different offices, so do the rules. Eg Bangkok it's almost impossible to obtain if you aren't doing 90 day reports. Pattaya however easy, just go in with your TM30 details.
The Resident Certificate is a standard request and needed or helps for all sorts of things, driving licences, bank accounts, registering vehicles... My local IO in Kanchanburi charge 500thb, and they write the reason for the request on the resident certificate.
Putting it in your wife's name would probably be easier...
for that to work, on the first year, he'll need a letter from his Embassy confirming. Most embassies will no longer issue it. However for his second year he can do that, with a 12 month history of doing so.