<p>I think you’re overestimating the “shock” of transitioning to college courses. Most students expect to have to work harder in college, particularly those who take BC calculus, which is often the highest level math course at most high schools. I’m in this situation now, and I feel comfortable with the pace of the material in multivariable calculus.</p>
<p>Additionally, I don’t see the need for most high school students to rush through calculus in a single year. If you did it junior year, you wouldn’t have any math courses left to take senior year. Unless your high school offers multivariable, or you take the course at a local university, the only other option will be AP statistics. As you mentioned, AP Stats often doesn’t count towards engineering curricula. Also, AP Stats would likely be at a slower pace than AB+BC, so you could lose any conditioning you gained the previous year.</p>