I don't know about the hammie but I have done 20+ hours roadtrip with cats more than once. If you haven't already take your cat on a test trip. I wouldn't sedate unless you really have to (some cats go completely bonkers in the car). Sedation impacts their ability to regulate temperature and respiration. Also some cats fight sedation and it just annoys them. So test a trip sedated if you think that's how you want to go. This is the most important step! Skip at your own risk!
Have a large good strong carrier that can handle cat pee and poo. Make a hidy nest in one part and a pee place in another if you can't fit a small litter tray. Bring disposable bedding (puppypads are good), a sealable plastic bag for soiled bedding, and disposable plastic gloves. Some petsafe cleaner and papertowels.
Bring some extra bath towels. You may need to hold kitty without getting clawed-- use a towel.
Make sure there are rules about opening the door-- everyone needs to check first that kitty is locked up safe before opening. He may come out, I have slept at rest stops with kitty out of his carrier.
Bring dry food, wet is rather messy and smelly. Make sure he is well hydrated before hand-- I suggest adding warm water to his food for a couple of days before leaving to encourage hydration. Of course that will mean a bit more pee but that's better than dehydrated cat. They can be reluctant to drink when in a stressful situation.
FYI did a family cross country once with a sedated cat, an unhousebroken puppy, a dog, and two turtles. Enjoy LOL.
Now sorry for threadjacking the hammie question I hope this helps!