Ken, My vac-pan2 is different than the short vac-pan2 (near or in the baseboard) shown at EZVacuum. My boss (my wife) doesn't like this type.
Ken, Distance to the bottom of your box is 14 inches from the finished floor. I installed mine without having to shorten the wall plate that goes between inlet and floor.
I have a problem you might also have. The internal electrical connection for vac-pan2 does not work when mounted to wall and does work off the wall if you hold it in the up position. It is sealed, so I don't know how the low voltage circuit is made.