That was the hardest part mainly because plumbing is my Achilles heel and I was stressed I would screw it up.
Since my holding tanks were from a wrecked camper and already had the holes and drains, I just fit them between the cross members where they would work and then made sure my shower and shitter lined up. My freshwater tank is under the bathroom sink. I made platforms out of 2x6 under the toilet and shower to allow me room for the drains. I used Hepvo traps
https://hepvo.com/ they lay horizontal and don't take up much room. I used pex for all water lines. It is flexible and easy to work with plus it is less likely to bust from freezing.
I didn't take any pictures of the plumbing install but basically researched it and used plumbing diagrams I found online.
