I put all my stuff inside my tent, zip it up, and leave my campsite all the time. It's only on very rare occasions I've felt "a vibe" that leaving my campsite unattended would be a bad idea. Chatting with your neighbors is a good idea to let them know your circumstance. It's not to have them be responsible, but just to keep a "neighborly eye". I've never lost anything to theft at a campsite or touring for that matter.