Clonazepam is used to treat anxiety in pets. Unfortunately with out having an established client, patient, clinic relationship I can not advise whether or not to use this drug.
The following article will give you information on the use of this drug as well as the recommended dose for your baby. I would recommend giving the lowest dose recommended.
I hope this has been helpful, please reply back if you have additional questions or concerns.
The clonazepam will help to sedate them, the dramamine will only help with the motion sickness.
There is not anything you can give with out a prescription that will keep them asleep, nor is it really safe to give something that would keep them asleep for this long.Knocking them completely out for that length of time could be dangerous.
You may want to try the clonazepam ahead of time to see what effect it has on them and help decide what dose is best.
Valium and xanax are also used in cats and you can find the dosing information for both drugs at the same site.
No the crates are a great idea just let them out every few hours to potty and get a drink.