Does anyone have any experience with an internship that requires 10-15 hours per week while taking 4 rigorous classes?
It all depends on how you manage your time. Some won’t have any trouble at all with that. Others will.
Lots of students take classes full time and work 10 to 15 hours per week. If you don’t also have a job and lots of extracurricular activities that are time consuming you should be able to handle it.