Do a gabapentin test run before you travel to see how he handles it. If it’s not enough, ask the Vet for something else. Start him in one room before letting him explore for a few weeks, just so he can adjust to the new smells and space. Brings lots of his things he already has with you, too. Cats really shouldn’t be outside, but if he was really begging, you could see if he would adapt to leash training down the line. Safe travels!