For a softer landing academically, I recommend he consider not jumping past classes that AP scores give him the option to skip. For example, if he has an AP Calc score that allows him to skip the first quarter, take the first class anyway. It will count toward GE and be easier than jumping straight into fresh material.
Calc is a large lecture class, but if it is not offered in the Summer Session, he can still use this strategy to soften things in the Fall.
There may be similar thinking for other APs if you let us know his major and what those APs are.