--You can build a P00P Tube out of large-diameter PVC, which isn't used TO go, but to contain and haul out the paper and whatnot. You can line it with a bag, or not, and you can put some kitty litter in there to absorb smells.
--You can double-bag gallon-sized ziplocks, and scotch tape some paper towels one layer thick inside the inner-bag for two reasons: opacity for the squeamish and mild absorption. A little kitty litter is good there, too.
At the latrine, you clean what needs cleaning if you're not one of the UL'ers that rub up against cholla or snatch unwitting squirrels for the task, and then fold over and stash in the bag. If you use wet-wipes, they'll help with the odor, but you'll need to occasionally burp out the moist air (dry is better in the tube or bag).
Animals will still attack this bag, even though you and your crew think it's gross, so you have to stash it in your animal-proof set up. If it's a P00P tube, you're probably okay, but the bag...no. Ergo, the double-bag method and maybe a third bag stashed in the gap, just in case.