Yes, I am aware of where it is and still think it may be valuable for the OP.
The OP wanted stops / things to do not too far out of the way they intended to drive.

The fastest driving route for the OP would not even go into Basilicata at all ; once you route the trip going through Basilicata you will see Paestum is a possible stopping point. Slightly out of the way, but not drastically so and in Italy the reality is no stop is ever on the way.
If they decide on Matera or on the Pietrapertosa/Castelmezzano as an overnight stop in Basilicata ; Paestum could be a day time stop before they get there.
Basilicata is one of the least populated areas in Italy and there are not going to be a ton of great options.
The OP may decide that Paestum is too close from their starting point of Naples, but personally would take the scenic even if stressful and longer drive time way through the Amalfi Coast ; then would be up for a rest by the time I got past Salerno making Paestum a perfect stop for lunch and some afternoon site seeing. From there continue on to either Matera or Pietrapertosa/Castelmezzano to reach in time for sunset ; stay the night and a few hours the following day before continuing onto the final destination.

What is your helpful contribution to where the OP should look into?

OP: if you are not already aware. Visiting towns by car along the drive somewhere else in Italy is not as convenient as it is in the US and other places. Towns often need to take some back roads off the main road, often you cannot drive into the town center so may have to park outside of town and walk in ; all of which takes time. Not to mention the usual caveat about it being unsafe to leave any valuables in your car when visiting another place. Make sure to research any ZTL areas near any points of interest before your trip so avoid them. GPS directions can take you right into them which can be a very costly mistake.