[Brantlyj]

If you have plumbing skills you could cut the shower line after it exits the bottom of the trailer, put in a tee, take of the valve from the kitchen sink tank, put on an elbow and a length of pvc to the tee. Then you can still use the combo black/gray outlet.

Of course if you have no plumbing skill you could hire it out. I can’t believe it would be terribly expensive. I doubt I would ever boondock but most of the State campgrounds are not full hook up so the full tank capacity would be nice.