Is a definite yes for the parking pass too, but leaving and returning can definitely a PITA. You should be aware that general parking areas are well west of the general exhibit area but EAA provides shuttle bus service. Due to the roads, the place is basically a one way in and one way out arrangement. EAA and local law enforcement do the best they can given the cards they are dealt. Unless you’re arriving really early in the morning anticipate delays due to volume of traffic. As they say…Welcome to Oshkosh!