Those ideas were great, but unfortunately Ambre didn't go with us on our trip. We had everything we needed for him packed up (food and litter; we had a litter box from his last trip up there), but he must have figured out what we were doing, and hid in our basement. We tried to act like everything was normal, but he didn't buy it. Mom and I begged him to come out, but he just meowed at us as if to say "
!". I offered to stay home with him, but Mom wanted me to come with the family. We just gave him an extra amount of food and water for when he came upstairs, and he had his litter box in the basement, as well as a supply of dry food and water if he went down.
I also thought that maybe the next time he went out and we wanted to go on vacation with him, we'd pack our necessary stuff while he's out, then when he comes in or if he's still sleeping, we'll get his kitty carrier and put him in it.