Typically, I'll just toss everything I don't need right now, in the car ( or saddlebag on the bike ) and take the key alone, though I rarely ( if ever ) lock a vehicle at a resort.
I manufactured towels with pockets for a while, but no one was interested in buying them. I sold only one, though I've seen a few "home made" here and there.
I carry an AANR or Travelites' canvas tote and put essentials in that such as sunscreen, book, paper/pen, business cards. If we're not staying overnight, I have a large canvas bag we put our towels in as well as the essentials. We don't wear that much going to a nudist park. I have some long tshirt dresses. Allen just has shorts, polo, and boxers. We usually keep our sandals on.
Besides, it is difficult for a nudist to hide something they may have stolen ;)
I too leave my stuff in my car. If I am camping out, most of my stuff goes in then tent. if I am just there for the day, I just leave it in the car.
Stay naked!
At the place my wife and I go to,we are members.We let ourselves in,park the car,and undress.Our clothes get left in the car.I have often thought of being nude when we pull in the gate,but I have not done that yet.I wear as little as possible when going to visit the resort.