Nothing like your long trip, but I just wrote about a brief weekend trip and how I ate more than I wanted, but did so much better than I would have in the past.
Exercise will help, and planning when you can... Allow yourself some of those special treats, but maybe if you have the burger one day, don't ALSO have the ice cream or the ... whatever... on that same day. Space it out. Pick more veggies when you can. Don't feel you have to "clean your plate". Let yourself have SOME and stop sometimes.
Keep yourself accountable for what you DO eat! Maybe write everything down? Then you'll at least be conscious of what you're doing and not become mindless or careless.
My 5 C's of healthy living: Commitment to conscious control, with the understanding that choices have consequences