Before you go, a good base of sealant or wax will allow the road crud to come off easier during the trip. Then, I’d recommend you pack a bottle of Waterless Wash and some blue WW towels, and maybe some DS and Single or Double Soft towels. Assuming it’s not more than light dust/dirt, rain spots, fingerprints, etc., Waterless Wash is ideal (anything more and you’ll need to just wait till you get back...you can also dilute Rinsess Wash 16:1 for a Waterless Wash-like solution at a fraction of the cost). For the inevitable bugs, spray then let soak for a while, and lightly rub off what you can. DS can also help with some added shine and protection. Glass Cleaner may be worth adding to the mix, but you can get decent results with the WW in a pinch. Brilliant Glaze will add some serious, albeit short term shine with very limited protection and is easy to apply quickly by hand. You might also consider packing some MRB to clean the towels along the way should you have access to a washing machine. Those towels are going to get nasty. Get and Adam’s bag to keep it all together.
Have a safe trip!