Some places, cant remember where but its probably Poundstretcher, Wilkinsons or somewhere, sell smallish kids wastebins with a lid, they look like old fashioned dustbins. Only cost a couple of pounds. You can spend a penny in them during the night and put the lid on. Quite civilised!
------------- Pally
The pen is mightier than the sword - but only if the sword is very small and the pen is very sharp...
my bucket gets filled with allsorts for the journey - always a loo roll (in case there is none on site or its needed for other reasons), and small stuff i might need quickly and that might otherwise be lost in one of the bigger boxes - torches for example. That way bucket is always emptied of stuff before it is needed and also serves a use as part of in car storage.
Take an empty wide, large plastic bottle ( large fabric conditioner) warm it in hot water and then cut the top off with scissors, fill it with stuff on the way down, use as required and then discard for on the way back, very eco friendly.