When visiting French friends and family and I always parked on the road side and never had any issues. But these were very rural areas..Didn't know that simply parking up at the side of a road in France was even an option, My motorhome experience consist of: saw it on ebay, liked it, bought it.
On my drives where I failed to find an aire I would pull up at 8pm or so and be gone by 8am. Never had anything outside the van etc. It really was just parking for the night. Never had an issue. That said I have done the same in the UK without any issues either.