N.T.
Can you bring a cot that is specifically his? Or maybe at home, do something different, but special about sleeping elsewhere in the house. Use his favorite pajamas, try to remain calm yourselves....if he throws a fit, sometimes just letting him have it and showing NO reaction, and try to ignore it as best you can. If that doesn't work, try other ways. Use his favorite pj's, sheets, toys...something has got to work. Maybe sleeping with YOU may help...he could just be worried about your dog. Maybe telling him or having someone he trusts that he knows will be with the dog may help....or you may have to bring the dog!! Several hotels allow dogs...while you are gone, if you have to leave the dog, you may have to have "crate" the dog....
Maybe having him sleep in the living room or backyard as a camping adventure with you or some of his friends...and really, really, amp up the enjoyment when he does stay somewhere else and doesn't have a meltdown.
If the anxiety is really bad, I suggest talking to his pediatrician. He may have to have some counseling and/or medication for the anxiety.
Hope this helps! Good luck!!