From GM: My father made his money with chicken eggs and as such he had automatic poultry waterers. Reading your article it seems to me they would be good for bee waterers as they basically need no attention to the keep water available to the bees. His were about a 6′ trough with a float controlled inlet from a pressure (home well) water source. They come in different sizes. Here is one source http://www.qcsupply.com/275005
The only problem I can see is getting the right size for the needs of the hives. I would put sand up to the level of the water. Sand has more pore space thus more water surface than gravel,( check with the civil engineering department at the college), and no chance for drowning. These waterers would have the same need to be raised above predator available level and covered with 1/2″ hardware cloth to keep out the birds.