Installing black water tank

You will want the deep end on the driver's side because the dump stations are set up that way.

Thank you. I want to know if the hole going from the toilet to the black tank is on the deep end of the tank or the shallow end. The black tank we are using slopes from shallow to deep. Should the hole going directly from the toilet be drilled into the deep or shallow side of the tank?

The hole going directly from the bottom of the toilet inside the RV. We are drilling down through the floor into the tank. Should the toilet hole go into the deep or shallow end of the the tank?

shallow end! as all poop goes down hill

Deep end so that you know the poop is close to the outlet and ready to go out - no worries about “it failed to slide” close enough to the outlet to be expelled.

I would try to put the vent on the shallow end and the toilet hole on the deep end. But that's just my opinion.

How shallow vs deep are we talking? I don't think pre constructed black tanks have that much of a slope. For physics sake you want some but nothing dramatic as it will decrease capacity. I doubt RV manufacturers put much thought into where the hole will go other than how does the tank fit in the chassis and where the toilet is on the floorplan.

Don't know much about the tank, but I do know you don't want sewer lines sloped very steep or water will run off and leave the solids. If need to go down much grade you step the line so slow flow, drop, slow flow.
Why would you force solids to travel any farther than needed in tank? Drop them in as close to where you expect them to go out as you can.

Isn't it going to be dictated by where the toilet is?

It is common practice to put some water back in the black tank after dumping, to stop the pyramid of poop. That water will be in the deep end, so I suggest the toilet goes over the deep end. That's the way is was done on my MH.

Richard