My suggestion would be to start w/ just a pee pad (we use the washable ones - they're really not that bad and far more safe than disposable ones, particularly for puppies that like to chew/destroy
. Eventually, once he's trained to go on the pad, you could move it into the tent. It may just be the tent - being closed in, etc. That's something your puppy may need time to overcome. My pups have a pen that they can see out of and we keep a pee pad at one end of it w/ their bed and food at the other end.
JMO
Good luck!