I installed a SeeLevel tank monitor system on my fiver recently. The hardest part of the job was gaining access to the tanks. My trailer belly is covered in Coroplast (the corrugated plastic stuff). I had to remove a black pipe propane line, the spare tire, and the Coroplast itself which is attached with many screws. I started at the front basement, and removed all the Coroplast up to the axles. The fresh tank (which is in front of the axles) could be accessed through a small cut that Jayco left in the Coroplast. Had I known, I would only have had to remove about 18 inches of the Coroplast on the "passenger side" of the trailer, from the front basement to the axles. The Coroplast was not nearly as difficult to re-attach as I thought it might be. Filling in the many "holes" (for various piping and other reasons) in the Coroplast with expanding foam was messy to do.
The SeeLevel system install instructions are quite detailed, and must be followed carefully - the system is a bit finicky - but the install itself is not hard. Each sensor attaches to a ground and to the original sensor wire. All the sensor wires are connected just before the monitor, with one lead going to the monitor. In addition to the sensor wires, the monitor just needs positive and ground. All the sensors send data on the same wire, and the monitor figures out which sensor is which.
Here's some pictures.
I removed the led tank displays of the old KIB system, and re-used the switch section. The remaining switch section is not pretty, but it works. I'll probably get a better switch panel sometime:
All of the waste tanks were the same size and had this label on them:
This is the black tank. You can see the long aluminum rod that comes from the handle, and the white hose that attaches to the tank washer. Also, the galley tank valve is visible:
Here's the installed black tank sensor. The sensors have to be cut to the proper length, and then you cut a specific circuit on each to tell the monitor what tank that sensor is attached to:
(continued in next post due to image limit rule)