Composting Toilet

No personal experience, but many people are using these on boats including a few friends. They are properly called "desiccating toilets" since little or no composting goes on. The #2 waste is mixed with some organic material which absorbs the moisture and dries it. The resulting mix is disposed of at intervals. It is legal in most jurisdictions to simply put it in the trash (same as a dirty disposable diaper). I think for most people a standard RV or boat toilet is a better choice, but there seems to be growing acceptance of the alternatives.