You can stay at the camp site of Madens Folkemøde, if you bring your own tent. 

The camp site os open from Thursday 1 June at 5 pm until Saturday 3 June at 6 pm.

Prices
220 DKK per person no matter how many nights you'll stay and how many people you're in the tent.
120 DKK per person if you are a student.  

There will be acces to bath and toilet at the camping spot. 

Check in at the entrance of Madens Folkemøde - find the camping near the church, a little bit hidden.