In disbelief that someone who has been a member for over a year has missed this:
Short answer to your question: Yes. All that stuff in the manual about long gun transport is there to keep someone from inadvertently, and illegally, concealing the gun. You are quite lawful in OCing long guns, either on your person or in/on your vehicle. The only way I see of getting into trouble would be with some LEO with a wild hair catching you in a GFSZ. I carry mine often when on my BMW, slung over my shoulder or secured across the rear seat. No problems, ever.
Enjoy the ride.