campsite theft ...worry/not worry?

People (bikers or car campers) typically leave their cooking equipment, coolers, tablecloths and associated boxes on the picnic table or nearby. Also folding chairs, etc. are usually left out in the open. Unless your campground is next to an urban area, you should not expect anyone to come onto your campsite. There are always exceptions, but all in all, it's a pretty trustworthy bunch who frequent campsites. I've always felt comfortable stowing my panniers in the tent, and taking with me only the valuables and other must-not-lose items. Don't stow food in the tent, though, or you'll likely return to find you've had critter visitors.

As for the bike, when I feel I need to lock it, I pass the cable through the frame and both wheels, rather than removing the front wheel, and around a tree or part of the picnic table.

Just match your security measures to the situation. It's natural to worry at first, but after you've camped a good bit, plain common sense will take over and you'll seldom worry anymore.

Lew