Agreed, I would not leave a hedgehog for more than one night alone, and even then only if I was going to be home relatively early the next day. Good luck with your search, Cashmere! If you can't find someone with hedgehog experience, I think your friends would probably be fine taking care of your hedgehog at their house, if there's a room where they can close the cat out of. I don't think there would be much issue with any of the animals getting along as I don't see how or why the hedgehog would meet any of the other animals anyway. If you can, have them come over sometime before the trip so you can teach them how to handle Erin and show them her routine for cleaning, food, etc. You can also prepare a folder or care sheet with any other information they may need to know (typical amount of food eaten, signs of illness or emergency vet symptoms, what to do if she hibernates, etc.).