I would ask your vet! The traveling might just be too much for that kitty! I know that at the vet clinic I worked at (I'm a vet tech) we would often get older and infirmed pets in for boarding. Does your vet offer boarding? If so, if anything untoward happened, your vet would be right there to treat. So much more is involved when you have a geriatric cat who has CKD. Also, cats who are stressed and not at home will often refuse to eat or drink. I'm concerned that if you are out on the road and this happens, your cat may require an IV bolus of fluids. This is really something you need to discuss with your vet, IMHO.