The vent system took the most planning. On the picture below, you can barely see the white 1 inch diameter PVC pipe coming out of the threaded fitting above the black 3 inch ABS drain line. The PVC pipe is attached to a 90 degree elbow and goes up through the bottom of the trailer.
The vent line comes into the trailer in the kitchen cabinet floor, just aft of the shower. It goes up the forward wall of the cabinet and into the wall between the cabinet and shower. The Tee fitting in the middle of the vertical leg is for a garden hose so I can flush the vent line. I expect that the vent will get fouled as it mounted on the side of the auxiliary tank, the clean out will keep it clear.
Inside the shower, the vent line comes through the wall and into a saddle fitting on the existing 1 Ĺ inch black water vent as shown below.
I made the saddle fitting from a normal 1 x Ĺ x 1 slip fit Tee fitting. I cut the fitting in half as shown below and then sanded the raised boss around the Ĺ inch hole so the fitting fit snugly on the existing black water vent line.
I used a long ľ inch drill bit to drill a pilot hole through both sides of the black tank vent, the shower wall and into the adjacent kitchen cabinet. I then used a piloted hole saw to drill from the opposite direction; from the kitchen through the wall and one side of the black water vent. I then installed a ľ plug in the remaining hole in the black water tank vent. The picture below shows the long drill bit in use.