Yes, we can do camping at Deoria Tal at night.
For that one needs to take the permission from the forest officials and there are some charges for the camping. The per person charge is Rs.50 which you need to pay to the forest department before pitching down your tents if you are already having with you.
If you don't have the tents so, you can get them at rent and the starting price is Rs.500 per tent.