In reply to RBonney:
I imagine most people on UKC would think it's acceptable to wild camp discretely above intake walls (pitch late, leave early, leave no trace) and bury an occassional turd well away from any water source. We don't tar ourselves or other "responsible" "wild" campers with the same brush as we would the large groups who turn a bit of wild land near a lake district road into a mini festival for their mates and leave litter/shit strewn around.
It seems a lot of us, myself included, are relectant to accept that van camping can be done responsibly as well as irresponsibly. Or maybe we do accept it and occasionally do it ourselves, but don't want to encourage/condone it in writing.