You'll need your Thai wife to attend immigration with you, along with proof of your marriage that's registered in Thailand. Some immigration offices might start the extension the day you apply, and some might add it to the end of your entry stamp. This is a generic list of requirements, as each immigration office sets their own requirements.
Do note: not every immigration office offers the 60 day visiting Thai family extension.
Because 90% of the people that book classes for soft power are never even going to see that school, let alone attend a single class. And some of the classes are only like 4-5 classes across 6 months, which hardly necessitates a 5 year visa. This is the reason many people think things will tighten up at some point, like requiring proof of ongoing courses or attendance when re-entering after the first 180 days.
Tell them you are traveling to Thailand and you want a tourist visa as you are traveling as a tourist. It doesn't matter that you qualify for something else.