Black tank best practices

Hello

We purchased a permanent site to place out travel trailer on.

What would be the best practise for using the sewer system on the trailer with the parks, on site sewer connection.

I'm a little iffy on just leaving it all open, as I don't want to have any leftovers stuck in the tank. Or are they designed to fully drain?

What are the thougths on this?

I don't really want to have to wak behind the trailer every few days and pull the drain levers either.

Thanks
Paul