Have a wonderful trip. In our case, we have not seen long car trips to have an influence on BG levels. One approach would be put on a temp basal that is a 10-15% reduction and test after two hours or so to see what adjustments should be made.
We drove Missouri to Virginia with the return trip tomorrow. Setting a temp rate at 125% did the trick for us.
Sometimes the excitement of taking a trip will result in a high and sometimes it will result in a low. We always left the basal and tested more frequently, adjusting as needed. We used to make long trips of 5 or more hours to hockey tournaments and really it could go either way that David's BG would rise on some trips and drop like a rock on others.
Our family lives 5 hrs away, so we often take longer car rides and Sydney always runs high. We don't pump, so I can't really help there, but I think an increase would be a good idea. I usually give a bit extra background insulin and do a correction if needed when we arrive. Typically, she is a bit too high for her normal snacks, so I bring cheese, pickles and popcorn twists. Usually, by not giving her a carby snack in the car she will come down pretty good by the time we arrive. I'd say maybe 3/10 times I've had to give a correction. As a side note, make sure you do have higher carb options, you never know when car trouble may hit! We got stuck on the side of the road in bad weather last winter with no more than 15CHO, and I was a bit scared for a while. (It turned out fine, but I was stressed!)