I was in Monza WSB in '11, and the camping is very funny.
Total mayhem including bikes hitting limiters, car engines mounted in shopping trolley's just to be revved, chainsaws with the cutting bar removed just to be revved etc but come about 12.30am all the noise stops and its quite peaceful until about 6.30am... I thought Assen was crazy (it is!) until I went to Monza
simplyhike.co.uk has a good selection of camping gear of all prices