My FW tank had the drain and vent/overflow lines hanging between the 2 axles. This was a pain in the neck, but I had a much lower opinion on this to access the tank drain shutoff. I ran 1/2" pvc lines to the rear of my trailer with shutoff valves on each line. Now I open both valves when filling. Once water comes out of the drain line (sorta flushing out the existing water in tank) I close that valve. When water starts coming out of the vent/overflow line, I close that valve. Now I don't lose water from the tank while moving to my camp site. Once I get set up on site, I open the vent/overflow valve. Always remember to open the vent/overflow valve when filling the tank. You can make a 40 gallon tank a little larger real quick. Don't ask me how I know.