In outdoor venues, you take a risk if you leave your items.
We did three booths (30 feet) with stained glass and my pens. We took down the products every night, packed most and got there early the next morning to get everything displayed again. In ten years, we were "robbed" twice that I can remember, in the nighttime. Both times our merchandise was recovered and returned to us on Sunday, when the "thieves" were caught. One, the "driver" returned to pick up the last load too late (6 AM). Crafters had already arrived, discovered the theft and notified police. Mom and daughter (hereinafter called the desperados) had gone through the big tent and chosen their merchandise. They had removed a load or two and were planning on one more, that was already stacked. The desperados were caught and under torture (well, they were asked) confessed and returned the goods.
The second one, a teenager bragged at a Sunday party. Local detectives had infiltrated the party (there was at least one honest teen there) and so, they were apprehended!!
We left our stuff hundreds of times, so it is probably less than 1% stolen and NO loss.
But, if I did shows with only my inventory, I would remove most of it (leave slimlines and cigars hidden under packing materials). It merits two trips to the car.