I've arrived with a 90 day spouse visa and plan to apply for a 1 year extension. Wife and I are currently in quarantine. By the time I get to Chiang Mai, open a bank account, transfer the required funds and wait for 2 months, I may be running short of time. Can I apply for a 60 day extension and before that expires then apply for my 1 year extension?  I read somewhere that you can only apply for one extension per year.

You can apply for a 60 day extension to visit your wife and then apply for the one year extension.

There is no limit on the number of extensions you can do over any period time. Some you can only  apply for once per entry.