For a syn cargo, there is nothing tougher and more versatile than the VersaTac's from Railriders. Light and mid weight versions available but they don't have a great color selection.
http://www.railriders.com/men-versatac-mid-pant-p-955.html?cPath=104_110
http://www.railriders.com/men-versatac-mid-pant-p-955.html?cPath=104_110