I've moved twice cross country. Drove both times with pets (2 dogs and a cat, and the second time with a toddler as well). For the cat we got kitty sleeping pills from the vet. Knocked him out for a few hours every day. But 11-12 hours is too much IMO. Like someone else said, give it a trial run before you leave to see how he reacts. Some cats will throw get sick with those pills. And whatever you do, follow the right weight/dosage recommendations. I almost killed the cat because I eyeballed it instead of measuring.

The one downside to that is if he's out and he has to go, he will still go. So you may have some messes to clean up.

We put the cat in one of the dog's kennels and the dog just rode without a kennel since she's well behaved. This way the cat had some extra lounging room and wasn't confined to juts his carrier. And we could also fit his litter box in there as well as some food. For water, we bought this contraption from PetCo that sits upright and dispenses water when it's touched. Otherwise if you leave water in a bowl, every little bump in the road will cause it to spill.