Overall, good points in the post. However, it is a bad idea for a student aiming for engineering to try and pursue college credit for an AP exam physics course, should the college even accept it for placement or credit.
I don’t know much about physics, but if engineering is the goal, start with the 100 level course, which will be foundational and will set the stage for other courses in the major.
I have two perspectives here:
In my son’s case, his 4 in AP stats did him no favors and he wishes he hadn’t sought college credit for it. He took the class as a sophomore in high school. By the time he needed to take a stats course for his major, it had been at least 3 years since he had taken a stats class. And guess what? Because he already had credit for AP stats (effectively the 100 level stats course, as far as the college was concerned), he was not allowed to take the 100 level class in college. He had to go right into a higher level course and by then, had forgotten most of what he learned. It was very hard and he had to play catch up. It did his GPA no favors.
My eldest child self-studied AP Psych because it wasn’t available at our high school and she thought she would probably major in it. Got a 5 and decided against trying to get placement in the next level class. She took the intro level psych class and was very glad she did. That foundation was very important.
APs are rigorous, but they are not truly representative of college level material. Self-studying isn’t helpful, for sure, especially if your high school offers AP physics. Colleges aren’t expecting students to have community college classes on their transcript.
Either ask to be placed in AP physics because you are looking for rigor, or take it in college.