We use a sewage lagoon on gravity so fairly easy to maintain.
We used to have septic at another place in the past and it was a concern not like you can hook up a trash pump and pump it into the yard with neigh bours..
Ran into someone at the grocery store buying lots of yeast. Says he pours it down the toilet and hasnt had the tank pumped in 10 years. Now much yeast per treatment, I dont know.
I really don’t know how you’d clean it. At some point things will have to change to either more primitive or better. If everyone is dead then I go get a pump truck.
I’ve got a honey wagon setup on my camper. It might be beneficial to look at intercepting the main and making a portable hookup like that so you can haul it off
i had my Septic tank cleaned clean 3 years ago $400.oo it hadn’t been cleaned in years but property vacant 3 years too guy said it looks ok.?.only a 500 gallon but just me using it.