Awhile back Jim over at Bison mentioned about saving soap chips.
"A use for soap scraps. Place several in a wash cloth, tie shut ( plastic security tie? ) and wet and use like a scrubber. I once saved three years worth of soap scraps and couldn’t think of a use for them. Now I can save again, as I hate wasting anything."
Instead of using a washcloth why not try an old nylon stocking. Tie the bad part of the stocking shut and fill her up with soap scraps. This will lighten the load if you are packing, the nylon scrubs you gently, and it air drys almost instantly instead of having a sopping wet mess to deal with when it comes time to head out of camp. The nylon can be easily be tied ( with a knot )at the long end and sways in the breeze. I used this method while hiking in NM to the chagrin of fellow hikers who spent several dollars on soap caddies.
Another variation is to use a lost mate sock in the same principle. However I would turn the sock inside out to maximize scrubbing.
Watch out for hotels in your area going out of business or changing hands. Inevitably they will be changing shower products to standardize with home office. you can pick up all the little bars of soap and shampoo you could ever use!
Be wary of a clean man in the middle of a mud fight...