@Brown *******
Hmmmm 🤔
Re-read your question...
Are you planning to leave Thailand during your initial 60 days or when?
IF you are entering with the Thai Tourist Visa you will get 60 day STAMP plus can get one 30 Day extension of stay ADDED to it.
ASK Jomtien Immigration office to be sure...
but I believe they do accept the application within 45 days.
Is it not possible for you to get the Non O Visa as retiree while you are in your home country?
And you mention avoiding the hassle on arrival by having a 60 day tourist visa...
Reality is that its not likely that Thai Immigration Officers will hassle you if arriving Visa Exempt Entry... there's NO guarantee that Thai Immigration Officers will allow entry with the Thai tourist visa either.
It's the airline which may ask to see PROOF of your flight departing Thailand within the 30 or 60 days STAMP you receive on arrival. ASK them for their requirements.
Having a Non O Visa is usually accepted as you are not a tourist.