Good camp sites & lanes in Wales??

[codlord]

Planning a long 4x4 weekend in Wales (maybe Llandidloes sort of area but not sure yet) - can anyone specifically recommend any good lanes/tracks in the area - or even a good alternative area in Wales to try out?

Also need a camp site - pref just a quiet field or something - don't want a busy family caravan park or anything like that.

Any suggestions or advice apprieciated.