I just have a roll of whatever is in the cuboard at home tucked under the seat in the cruiser.
Although I spend most of the year out bush, I'm rarely more than a few hours from proper facilities (we build a small town wherever we're working)
If you do need to take a MMMM in the bush, bury your waste but burn the paper. In dry climates like ours it doesn't break down, and in areas that are frequented for overnight stopping its disgusting to see a used bit blow past that some curious critter has dug up from the 3" of topsoil someone considered sufficient.
Sean