After a few mishaps with key ingredients left behind as the car pulls away, we realized that we have much better success with actually doing vacation baking ahead of time. We bake batches of scones and muffins, wrap them individually in plastic wrap, and then collectively in aluminum foil before sticking them in the freezer. They'll actually keep for several weeks frozen this way.
The morning of departure, we pack everything in a cooler - as an added bonus, the frozen scones and muffins double as freezer packs to keep everything else cool! By the time we arrive at our destination a few hours later, the baked good have usually only just started to thaw. If we're planning on eating them the next day, we stick them on the counter (or leave them in the cooler, if camping) to finish thawing. If not, we pop them back in the rental kitchen freezer.
Reheated in an oven or even just a microwave, these breakfast treats taste just as good as fresh. When camping, we wrap the muffins in tin foil and heat them in the coals of our campfire. Don't forget to take off the plastic wrap first, though!
What other make-ahead meal tips do you have when vacationing?