When I'm where I'd like to go camping and there is no posted location
for such activity I'll start looking for buildering locations. These can include abandoned industrial facilities, unrented commercial structures,
or the larger bridges. Mid-span river channel footing is best by Abseil
and Jumar on fixed sheathed kernmantle tied to a steel support. Free
climbing a static rope tends to kill too easily. Technical climbing skills
let me scale man-made materials that face various high-rise. Rooftop tenting rarely has another party scaling same structure for over-night use. Never open any doors or windows. No campfires. Throwing hot
squat at passer-by also is ill-advised. Try to act like a conundrum.
Two is a crowd in my opinion. I can see how around twelve
could be a handful. If your party lacks any buildering expertise
then Plan "B" would be to start lifting man-hole covers. Most have a
fixed metal ladder inside. Antique stores usually sell required entry tool for a song. Electrical conduit junction vaults could easily handle twelve campers, are usually dry, and vent the heat. Do not piddle on cables as they aren't idiot-proof. Can't recommend storm drains or sewers but abandoned cellars can sometimes be had by inspecting leveled districts that were rezoned commercial or industrial.
Beware of brush covered wells or privy shafts.
