Has anyone installed/retrofitted a tank monitoring system on their 40.5 or similar holding tank? The legacy pneumatic system on my 1994 40.5 no longer works, and thus I have no tank monitoring. I don't worry so much about water, but I have no idea how full the waste tank is, and that bothers me. I read about the SCAD solo ( http://www.defender.com/product.jsp?path=-1|51|2234305|2234306&id=1249539 ), but I am not sure if this is installable. I also don't know if there is an easy way to access the tank at all. Any ideas? Thanks!