Best Composting Toilet

What type of toilet (composting or chemical) would best suit this situation?
The toilet would serve one person for 8 hrs a day, 5 days a week. There is minimal water available.
The best I have seen is a small chemical unit designed for camping. It is a relatively small cube shaped device with a manual pump to fill and flush it and a reservoir to hold the waste. It is adequate for a couple of people for several days.
When full you simply open the reservoir and flush down a conventional toilet. Because of the chemicals the waste liquid is fairly unoffensive and easy to deal with.
http://www.rei.com/online/store/ProductDisplay?storeId=8000&catalogId=40000008000&productId=48044284&parent_category_rn=4500612&vcat=REI_SEARCH
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