great idea!
I bring everything on your list plus:
bottled water
baby wipes
the small container of rice that takes 1 minute in the microwave with nothing added (perfect to give a bit if they get an upset stomach at all during your time away)
pee pads
Also its important to make sure you re-check their tags and that they are up to date with your cell phone number or another place you can easily be reached while you are traveling.
My vets business card in my wallet, should an emergency occur and another vet need to contact them.
Make sure you have proof of rabies, their tag or paperwork if they dont wear the tag.
Their bag is usually as big as mine
