I am doing a canoe trip with a mate next week, and we camping under tarps on the river Gt Ouse. Now I like my comfort, and going to the loo in the early hours when it is raining can be a bit of a drag if you only have a loo roll and a spade!
So, I have ordered one of these for the trip;
http://www.popaloo.co.uk/
OK, not exactly rough camping, but I'm getting on a bit you know!
I reckon that this would also be ideal for people with small campers with limited facilities.
I will write a review when I am back from my trip. (without too much detail!)