Yeah. It' kinda crappy how that happens.
I will attempt to repair that..
If you are actually referring to installing a MSD Portapottie that is designed for plumbing in...
I did mine last spring.
The holes in the liner are such, that the big ones will be covered up.
Our deck pumpout and the vent are vertically aligned, just forward of the bulkhead. I will be making a matching wood cover for the hoses from the shelf to the deck. Could be used as a good raceway for cables in the future.
The hole, down low, is hidden behind the pottie.
So if someone wants to remove the plumbing, they could cap vent, remove the hoses, reinstall my wood cover.
Only the hole down low would be visible, and that could be covered with a sheet of something.
My point is... It is relativeltly easy to take it out without it being a visual eyesore..
A normal head would be similar except for the flush water intake but i would likely try plumb it to an existing thruhull.
Leaving the large hole in the cabin sole..which i see as the big issue if you ever remove one.