When it comes down to it, is there any way around the 20+hr/week student class load in order to continually be eligible for a student visa in Spain?

What I’m ultimately trying to do:
I’m currently a USA citizen. I expect to be visiting Spain in about 1-2 months. I’m going there to decide if I want to truly start the next chapter of my life there but I want to know if there is reasonable expectation to think I can become a legal resident of Spain so I will feel comfortable in building a life there and eventually do things like feel free to occasionally grab a flight to other countries (USA, Italy, France, Thailand, etc) and back again without a fear of getting deported back to the US, fined, etc.

Back to the specifics of my question:
I know the Spanish consulate here in LA (where I’m from) state on their website that they want to see a “Letter of Acceptance” from the college I chose to study in Spain as part of the process to get a Student Visa. One of the things the consulate mention on the site is the idea of having 20+hrs/week of classes.

From those that have actually applied for a student visa:
Did you’re “Letter of Acceptance” actually mention the number of hours you will be attending school? If not did it go thru just fine?

The reason why I ask is I already have my degree but I would like to take one or two business classes (much less than 20hrs a week) to strictly benefit my existing self employed business. 

Please let me know - Thank you so much!