Okay, I've been reluctant to post this because no matter how I say it, it sounds strange and embarassing, but what the heck, it works for me, and if you try it, you'll be convinced, too.
About 2-3 weeks before your trip, begin drinking three big glasses of Metamucil or some other fiber supplement every day. I believe one can take pills now if drinking that stuff is not your, well, cup of tea. Continue this through your tour.
Why?
Well, let's just put it this way: It will make your #2 potty breaks much less of a chore because your stools will be firm, shiny, uniform size and shape (I can't believe I'm writing this), and a breeze to pass. Most of all, you will find there is very little "clean-up" work afterward. If you've camped a lot like I have, and if your diet on the tour involves a lot of powerbars as mine does, then this can be a real morale booster as you hover, sweating, swatting flies, over some stinking vault toilet in the middle of nowhere.