I don’t believe a warrant is required if the car is not opened. I could certainly be wrong on this, but I believe a dog alerting on the closed car is considered probable cause for a physical search, just as it is at a border crossing.
OK, if what you say is correct (someone else please step in and set the record straight if he is not), then at that point could the "suspect" insist that a state police officer or a supervisor be present during the search?
The problem is, at this point the cop is already pissed off because the "suspect" has "inconvenienced and disrespected him", so he may justify planting something in the "suspect's" car because "the guy deserves it for not being a sheep".