The PO had a welder raise the center rail section on the stern to be the same height as the stern seats. Now there is a lot more clearance for the tiller to be raised.
With regard to the flexible conduit question; I used a piece of 3" plastic pipe normally used for landscaping drainage. It's somewhat bendable and was able to conform to the curve of the hull inside the coaming.
You said you will be adding a second tank with macerator, y-valve, etc.. You may consider that with a MSD Sanipottie, you could simply have a second 2.5 or 5.0 gallon tank. Just put the caps on and find a place to stow the full tank. Maybe secured it to the stern rail, until you can dump it. In the pic below you can see the carry handle behind the hose connections. Just remove the hose connections and replace with the provided caps. That's what I like about the MSD's simple to install and provides the ability to manual dump if no dump stations are available.
