As with most boxing matches, a cock boxing match should be held in a boxing ring. Try to make a homemade one. The smaller the space the better(trust me).
how to make a boxing ring
But not many people have access to a boxing ring so an alternative is to mark an enclosed space with tape or a marker, specifically a space which has access to a corner in the room
If not, try to use a king sized mattress but make sure it is securely fastened to the floor
Even better, try and use a wrestling matt
or tatami matts
Its even better if your space has boundaries to support you.
What really matters though is that enjoy your fight but sometimes your surroundings can help you kink things up a bit ;)