We've stayed at Camping Municipal Plan d'Eau - but it's a few years ago now. It's quite handy for the motorway, in fact just off the roundabout as you exit, and not a bad site for overnighting, but I wouldn't want to stay for a longer period there. Big pitches, easy access, small bar, toilets not dirty, but not shiny clean either - accepable is perhaps the best word - some English style and some 'continental'. Shower OK, so for overnighting OK!
The Caravan Club lists four other sites within 10 kilometres of Villfrance - if you need the other names get back to me -but I'd stay there again if I ended up in Villefrance at the appropriate time on my way home.