I remember the term bivouac from my rock climbing days, frequently shortened to bivvy
http://www.backpacker.com/gear/article/0,1023,2261,00.html - similar UK and Oz sites

I also saw sites that indicated that anglers seem to use the term for a tent. They would therefore be able to have a bevvy in their bivvy.

http://dictionary.cambridge.org/define.asp?key=bevvy*1+0