I'm interpreting the word as what it means and how it is obviously being used. No one takes "campsite" to mean "the literal space occupied by the tent’s ground sheet" unless they are playing some silly sophistic game. Here is what it means (pick your own source ... they are all similar and none agrees with your definition):

"A campsite is a designated area where individuals can set up bedding, sleeping bags, or cooking equipment, such as stoves or fires. This definition encompasses any location that allows for sleeping or cooking, regardless of whether it includes a tent, lean-to, shack, or other structures."

And here's the Wikipedia description, which notes that the English "campsite" is equivalent to the American "campground", but that is broader and neither is so absurdly narrow as your words:

https://en.wikipedia.org/wiki/Campsite

> would understand that the tent got soaked

I already refuted this nonsense ... there is no reason to think from the OP's description that the tent got soaked.

> To use an analogy, think of ...

I don't need any help with thinking, especially from bad analogies that are flatly contradicted by the OP's description. What's the parking lot analogy to building dams?