we've got 2 x 55 gallon drums tacked end to end buried right now with 20-30" out of the ground

would you use that as a "riser so it's flush with the bottom of the "box" the seat is mounted on?

then vent the drums with an elbow and pipe??

or bury the drums deeper and just run a couple of vent pipes through the "box"?

I don't think we need to worry about filling up the thing even dug as it is now

We're talking a few years use maybe 20-30 days a year by 2 people

gonna be a big big upgrade from the ole lined 5 gallon bucket that's for certain!!!