I think u can camp at all three locations. Khanian, Kaghan and Naran.
Khanian Pine Park premises is good option.
Then in Kaghan, go down towards left of bazar where 2,3 hotels are situated. One of them has lawn which u can use for camping by paying a nominal amount.
In Naran, u can camp along with tent city and can use washrooms by paying fee to some tent owner there.
You will see hundreds of tents in Naran in season so no issues.