_____________________________________________You could probably safely get away with it but increasingly technology is catching up. There are things called weight in motion sensors (WIM) which coupled with automatic number plate recognition measure your vehicle as you drive over the sensors buried in the road and check if you are overweight. No doubt the fine is issued equally automatically!
Given where you live, near a port, I would expect if there are none near you now, they are coming.
yep! as we speak these roller weight devices are being installed in certain parts of France...not really about weight its about getting more money from the motorist