Our low point drrain velves are also between the black and grey dump valaves, but they're very close to the outside edge of the trl and you'll miss them unless you slide under and look up and toward the side of the trl. I took the drain caps off and put 1/2" NPT valves in place so I could just open and close them without all the water running down my arm as I tried to take the caps off.
2012 Winnebago "Journey To Insanity" 40U
2008 Dakota Sport 4x4
2004 Subaru Baja - DW's
2006 Honda Shadow Aero - TOAD for now.