How much stuff shifts depends on how rough the roads are getting to your destination, and how hard you hit those rough spots.
On a cross country trip, we once hit a stretch of freeway through a city that shall remain unnamed where every expansion strip seemed to come with a 1 foot gap, and for several miles every one of them felt like getting hit on the butt with a sledge hammer. And needless to say, you couldn't drive it at less than 55 or you'd be squashed like a bug by the trucks. Things were pretty well shook up when we finally landed for the night. Had to catch several things the first time we opened the 'fridge.
But as others have said, relax, you'll figure it out like we all have. It's supposed to be fun, don't over-think it.
