We often don't lock our van, and don't use the wheel clamp. We also leave loads of stuff (table, chairs, loungers, food, wine, small oven, grill, crockery, books, etc.,) out in the open awning - and usually don't have the front or side panels in. One time during a rainstorm our very kind Dutch neighbours put everything inside the van for us and closed the Heki!
The only time I've had any problems was from a site in Sauve, when I had money stolen from a Canvas Holidays tent - the site owner said that it was gypsies who were staying locally and who crossed the river to get into the site.