You have to recalibrate your sense of “tiers”.
Roughly, you have colleges with acceptance rates 20% and below, which are first tier. Next tier is ~up to 40% acceptance rate. Next tier is 45-65% acceptance rate (ie., a majority of applicants are admitted). Next tier is what is termed “moderately selective”, ie., not open admission but close.
If you attend a strong, well-known prep school, use the college advisers there.
Requesting, politely and with a rationale, more than the 2 AP’s you’re currently authorized to take, would be better than those online classes you plan to take (which would not help your admissions AND would likely take time from something interesting that COULD help you with admissions).