My 2011 Four Winds Chateau 28A is the only RV I have had where you cannot look directly into the black tank. The pipe goes straight down to a 90 degree elbow that I assume goes into the tank am not one to crawl around under my RV to verify where it goes. I am too old for that. When it stops working I will look.
The toilet bowl is the shallowest I have ever had. I would think some kind of half step up would work fine. I am near six foot tall and have considered putting in a step. Then I wonder if bending over to touch the floor has benefits.
There are no furnace ducts in that area. The hump/ boxed off area is because of the wheel well. The bathroom sink it the end of the line for the hot water system. So when winterizing with pink stuff the bathroom hot water valve should be opened first. It is the longest water run in the RV. All the hot air ducts are on the driver’s side. The longest one is maybe six feet. The bathroom sink feeds the black tank.
I think dropping the toilet down may be feasible with some reframing of the box it sits on. For me it is not broke, just inconvenient, so I have never considered fixing it.