Longest I've spent was 5 days in Lech. I brought all foods that didn't need to be cooked, and I admit that by the
last evening I was staring hungrily at Stan's hot food, and he was staring hungrily at my remaining chocolate bars
(we all had plenty of food left, but I was tired of mine and he was tired of his...). John, being a vegan, I have no
idea what he was eating...
Camping in Lech is *easy*. It's warm, the humidity isn't as noticeable as when you are camping in colder
caves and everything gets cold and clammy. It's not much different that hiking outdoors on rough terrain since you don't have to drag your pack for thousands of feet. I've camped several days in Kentucky caves and it took a lot
more work, and hot food was more appreciated. I probably burned twice as many calories/day in KY than in Lech.
I have been run over in the middle of the night when we camped in the middle of a packrat trail. No biggy once we figured out what it was, moved over a little, and hung our food and water. I agree with the others who discuss impact, camping in a cave has much more impact than simply traveling. On longer trips you have to weigh the impact of multiple trips into the cave to get the same work done vs the impact of camping, but fewer trips in and out. Camping should not be done recreationally, except maybe in very heavily traveled caves, or commercial caves.
I have never felt the need to exit the cave once the time was up, even after 5 days I would have been happy to spend more time in the cave as long as we were doing stuff. I dunno about 18 days, SG has that one on me!