Everywhere I cruise there is a marina and 95% have pump out stations
You are fortunate with that. In my case, Bay Springs Marina has a monopoly being the only marina on the lake or in the region. To get to one to the north, it is a 10 hour, very boring, motor up divide cut to Pickwick Lake. To get to one to the South requires a lock through at Jamie Whitten Lock and then a 5 hour motor to Fulton.
On the other hand, because the lake is largely undeveloped, for nine months after Labor Day and before Memorial Day, during the week I pretty much have the entire lake to myself. You have to take the good with the bad. And since the Wag Bags are soooooooo much easier there is no sacrifice for me using them instead of an installed head or a Porta-Potty.
I think pump out is free for boats in the covered slips at the Marina and for major fuel buying transients. But the covered slip boats pay a much higher monthly fee and have metered power they pay for separately. And filling up my three gallon gas tank does not impress the Marina owner. It is often considered a hassle if he has to pull off a tech he is billing out at $50/hour to go unlock the pump and fill my tank.
He prefers that I buy my gas on the way at the ethanol free station a mile from my house.
When your cruise is over I hope you write up a synopsis. I've never done a cruise that long on my 23, generally 3-4 days max.