I dont .. what size board do you ride?
I've had my board (a 156) in my car on the 40 side as well and didn't have a problem. Maybe you sit a lot further back than me. I'm only 5'8".
Another problem I run into is having subwoofers and an amp in the trunk. It all fits but it takes some maneuvering (not to mention making sure water doesn't touch any of the electronics).