It's starting to make more sense now.

First, I need to replace my wet/dry cam.

Second, It looks like I have two options for pumping out the holding
tank: 1. Through the deck fitting or 2. Through the 1.5" hose exiting
the hull next to the fresh water intake seacock.

The whale pump appears to pump from the tank, go through a vented loop,
and exit the thru-hull. What I am still confused about is that the
pump out deck hose is connected to this as well. Is it as simple as
when the thru-hull is open, the whale pumps out through it? Otherwise,
I would pump out through the deck fitting.

I do want to note to everyone that I know to not pump directly to the
lake as I am inland.