[Daryles]

What the guys above have said.
I would only add, when you use your black tank flush, keep an eye on the black plastic anti siphon vacuum breaker valve under the bathroom sink. It will be attached to two white PEX pipes.
They are notorious for failing/leaking. When you turn the water on to use the flush system, have DW watch for leaks under the sink.
Also mentioned above, get clear elbows for your sewer hose so you know when it's done.