If it rains, I think there's 0 chance that anyone would blink if you put up a tarp for additional shelter.
You're also more likely than not a stone's throw from a cheap municipal campsite that at least has a restaurant attached to it with a Michelin Star. This is France, after all!
You're also more likely than not a stone's throw from a cheap municipal campsite that at least has a restaurant attached to it with a Michelin Star. This is France, after all!