A couple of years ago, I pulled my camper from Cary to Yellowstone and back. The only enemy territory I had to pass through was Illinois. I figured I'd stick to the interstates, not spend the night there, keep the gun unloaded and hopefully not get harassed by some cop who didn't care about FOPA. Well, outbound, I would have had to either stop at 2:00 pm before I entered IL and add a day to my trip, or drive till very late into Wisconsin. I chose to do neither and spent the night in an IL KOA. I decided that if I was stopped and he asked me if I had interrupted my trip through by stopping in IL for the night, I just wouldn't answer. Burden of proof would be on him, right?
Returning, we wanted to see the St. Louis arch. There's a great little urban campground just across the river in IL, and not a good alternative. So once again I spent the night in IL, though when out and about I didn't carry. Couldn't carry in the arch anyway.
All you can do is shake your head at the stupidity of some of the gun laws we have.