>>1953280for starters, you don't explicitly need a bunker, unless that's your intended goal. In which case, yes, do so on your own property without telling a soul
>Where will you put the dirt?something small (pic related) is the size you're aiming for. small enough for a stove, bed, move to room around and shit as well as store your belongings. It's not a complex sprawl, just a hole in the ground maximizing concealability.
>How do you plan on supporting the walls and ceilings?by making them as close to the surface as possible to provide free and easy ventilation (< 5 inches below surface) without sacrificing concealability. Excess moisture is taken care of as well with a design like this.
>You need a good understanding of the soil that your taking outYes. if it doesn't pack well or retains too much moisture you're screwed
>is it a permanent thing?You can live in it indefinitely without extreme loss of comfort, but it's replaceable if it gets found/destroyed. The idea is to have one being used and one in reserve within a day's hike just in case