I'm a "planner" too. I like to be prepared for "unforeseen circumstances" and since you did mention "yarfing" - that is one area that just did not occur to me until the very end of my son's many car trips to the Radiation center. In the car I had water bottles for him, towels, tissues but no pan for him in case of nausea which progressed to "yarfing". It was at his "graduation" - last Rad tx - that he got a throw-up bucket (a square dishpan). At several previous trips, when the need arose I would have to pull over for my son to open the door and lean out and let it go. Of course I had to follow his directions like "not here, Mom ! - over there - up the hill - not in the driveway - near the bushes, etc. etc.

So here is what I would recommend: Have some towels, wet washcloths in a plastic bag, water, and a small colorful plastic dishpan with paper towels in the bottom (for easy clean-up) and paint a smiley face on the side. You could put the dishpan on floor of the back seat so your husband doesn't see it and possibly get the idea to use it. He may never even need it - but it helps to be prepared.