I personally took AP Studio Art and I have to say that it was one of my most time consuming classes I’ve ever taken as I had to have an art piece finished every week. It may be easier if you are doing photography pieces rather than drawing or painting. Just a thought to consider but I knew people who had similar courses and they did fine. It’s a matter of how well you can handle rigor and how disciplined you are in putting the time and effort in your classes. For example, I love working with numbers but when I took AP Stats, I struggled because it’s more of a data driven course. The plus side however is that there are less formulas to remember! 
Good Luck!
Elite colleges make it clear that 'most rigorous ’ is not equivalent to 'all ap’s '. I supposed it’s a losing battle now but I hope someone educateq your school that colleges never thought the mention ‘reasonably’ would need to be added to 'most rigorous ’ when they asked for 'mist rigorous ', especially when they make it very clear on their admission pages that they DO NOT want to see all-AP schedules.
Don’t forget to retake statistics in college, where the class will be more complete/in depth (and may have different versions: social science, biology, business…) as, if you take it in college, it can go on the line for 'relevant coursework ’ regardless of internship applied for.
All I can say is “Shame on the Head of School.” Best of luck.