Stop being lazy and going right by the heavily used campsite areas. Hike way up off the beaten path and far from any agua, do your thing on a flat rock, smear it out very thin with another rock.
The sun takes care of it shortly after. Welcome to crapping in the mountains.
The smear and dry method may be appropriate in some rocky mountain areas where you can't dig a cathole, but not so good on Mt. Whitney with 200+ people a day smearing it around, 17,000+ each season. It's just too many people and they tend to camp in 2 main areas. This is where toilets are the best solution, in my opinion.
