Blind Spot Signs for French Travel
I have just read a posting on another Motorhome site that gave some very important information about travel in France apparently since January 2021 ALL vehicles over 3.5 tonnes (including motorhomes) need to display Blind Spot Stickers, to both sides and the rear (French kerb side) of the vehicle, there are massive spot fines that can be issued and they mention point on your driving licence, for more detailed information search for “Angles Morts”
This link tell you more, but use google translate
And another here
Theses stickers are on eBay just under £6 for three, magnetic ones are also available.