We just completed our install of the Seelevel II tank monitoring system from Garnet Technologies
www.rvgauge.com. You can access the review from the main page under Product Reviews or by clicking on the following link
http://www.5thwheelforums.com/seelevel.html
The install was very easy for the average do-it-yourselfer with common hand tools. We elected to solder all the connections for a trouble free system which added somewhat to the time but the total install took us almost 5 hours - the bulk of which was used removing/re-installing the enclosed underbelly in our Wildcat 29BHBP.
Overall this is a great system with external sensors that read 0-100% - no more dirty sensors or Empty 1/4, 2/3, Full indicators.