I get a kick out of the folks with head plumbing nightmares... Believe me, I used to have them too, but not anymore. My 40+ year old boat has a gravity head, which is a toilet on top of a holding tank that uses a bit of freshwater to flush if your 'aim' isn't accurate. There are no hoses or vacuum systems, just a direct drop into the tank.
My worst job is backing the boat into the boatport when I get home. It's that last 20 feet that gets me every time. Here the slippery grass frustrated me no end.
Here I tagged the boat port supports while not paying attention backing in.
Sometimes it's a slam dunk even with another boat in the boatport.
I regularly kick myself for planting that tree there 20 years ago.