I empty my HW tank between uses using the low point drains.. I open both and then open the pressure relief valve on the HW tank and it drains out the bottom of the tank thru the cold water line. I get pretty much 6 gallons of water out (I put a bucket under the drain). This is the first trailer I have had that has the "rod" in it.. Guess I won't know if it does any good for a few more years, but that's what I'm doing for now.. I have removed it once already, but that was before I started doing it from the low point drains..
Good luck! Mitch