hi have a look at this site.
http://www.gaaspercamping.nl/eng/index.html
it is at the end of the metro so it takes about 20 mins to central station.
i find it best to get a travel pass for the metro that can be used on trams and bus unlimited for 1 2 or 3 days.
there ar a couple of other sites but i find this best.It has 24 hours security and a pass is needed to get in at night.
showers ect are cleaned very often and the rest of the site is kept very tidy.
hope this helps
bedge