I personally use this http://www.uribag.com/

If I don't want to get out (e.g. Amazon jungle, dark, critters on the floor etc...)

Grap the uribag, open it up, sit up, put it in, do your thing, close the cap, get the used pee bottle/bag in a peak bag type of thing/gearhammock, ground, fall back, cover with top quilt an dream on....

Grtz Johan