Here's my own take on a hot water set up.  One of these days I will upload a full description of this, but here are some pictures of the setup.  http://www.flickr.com/photos/9769028@N07/

The setup basically uses a pressure activated surflow pump.  The water is tapped from the existing line under the sink via a tee. Water is also able to be drawn from the existing line through the stock pump. (there is no check valve).  A switch allows me to use the stock pump for cold water, while the surflow is used for hot inside or outside the van.

I put a quick connect valve through the city water port that is self sealing when disconnected.  This was one of the key components, in addition to the pressure activated surflow.  The water flows outside the van into the eco-temp, and then a 2nd line goes to a second city water inlet that I cleverly hid behind the old refrigerator and exhaust vent that I don't use anymore.  This in turn goes back to the sink inside to allow for hot water there. A 3 way valve diverts the water for outside use.

I'd say it takes about 3 minutes to hook up, and uses the stock tank and stock propane.  Took me a long time to design, but only a couple of hours to install.  I am totally happy with the setup.

Troy