Why is not clear to you? You even say it yourself, 2 months before.. So what do you think will happen?? You won't be getting the extension... If you can't put the money in the bank in time? use an agent..
no 1 month extension is available for retirement visa.. you'll be at the mercy of the officer and possibly they will need 'incentives' to smooth the process because of the situation..
Getting around the rules is exactly what he could need and what agents can do..
Retirement visa will be far less hassle than spouse visa.. Conveying your licence to a Thai one is easy to do yourself, highly recommend doing this in Rayong.. It is appointment only now apparently.