The Douane guys are very tricky in France. If you fly over the country maybe they get you next time!!. I read in some places see Flyer forum guys that there are problems in France. Those guys they look for N reg. So it is better to visit the Douane guys. But it is also a good time to let the pax have a break and a cofee. 2 hrs is a max in a small plane. Better to be safer than sorry I think in France. The engine also has a rest cool down and get ready for the next waypoint