Hi @Amy276,
That's really odd. You can't charge him extra guest fees as he does not enjoy the facilities as you mentioned in your listing i.e., bathroom, bed, towel etc.
At the same time, the extra guest should not be around your home compound as he is considered as a stranger.
All you can do is to perhaps remove the hammock, if that is possible, to signal him that you don't compromise such behaviour. It is definitely odd. It is indeed a private property, not a hotel.
Have you made it clear to your guest, again? There is no such thing as extra guest, just sleeping outside.
All the best,
Zee