There is no way to opt out of the toll package when picking up your car, it is only by closing the pass can you avoid that being used. However, most car plates are registered with the toll contractor even if that is closed. Best option is to find a car that does not have a toll pass inside it (out of area car), but that is also not very likely.

If your dashboard portable tag doesn't get picked up at the toll scanners and they go to plate match, it is still possible that Avis's toll contractor would get picked-up for the plate match before your account. Of course, you just have to give it a try.