Yah, I had a popup until this fall when I got my TT. But I used to leave tons of gear (Coleman propane stove, propane grill, radio, silverware, plates, etc) all out on the picnic table when we left. I would even leave the camper unlocked. We would be gone for 4-5 hours at a time some times...never any problems. In hind site, I was probably tempting fate quite a bit even with a relatively low crime rate in rural midwest. But then you likely have a lot of people from outside the area at these campgrounds too.
I will take this as a good reminder next year with the TT and geny and other equipment. Our campsite will probably look a little bit more inviting now than it used to.
Bruce