Within the provisions of the district Wild Horse Acres is in, there is nothing against building an underground house.
A bare bones prestressed concrete building 30 feet wide and 200 feet long could be built for about $100k. Included would be a 400 square foot hydraulic elevator, power generating septic tank, thousand gallon water storage, environmental conditioning, kitchen, and bathroom. The biggest expense would be the hydraulic elevator because it would be necessary to lift ones car.
The more one spends on goodies, the more comfortable one would be. This is true with an above or underground home.
Underground would be safer than above ground. A fire would go right over the top and one wouldn't event know it happened. No accidental spent hunters rounds going through this place either. No windows to get broken. Will not fall down in an earthquake. If a tornado went over the top, so what. This type of home would survive the ash cloud if Mount Lassen blows its top.
Beside physical safety, one would not be found easily. The average burglar wouldn't know where you were, let alone overcoming the problem breaking in. The average person wouldn't see where you were from the road or from the air. It would take very sophisticated imagery to detect your presence from the air. Unless a very sophisticated determined person were to stalk you, it would be like disappearing from the face of the planet.
Heating and cooling would be cheap. Five feet of pumice volcanic rock roof would maintain a 70 degree habitat at a tenth the cost of the best standard insulated house built.
Entry and exit would be by elevator. The car, boat, and horses would all be kept underground. When not in use, the elevator is kept up so motorcycles, dune buggies, cattle, and horses would run over the top. If the place got a little too claustrophobiac, bring down the elevator, put a comfy chair on it, and raise it. In the middle of the day, or the night, the space feeling is immense. Sitting on a reclining chair on a moon lit night, not a sole in site, no house, no car, no nothing but nature all around. What a feeling! After a while, simply press a button, go down, drag the chair off platform, press up, and go write your novel.
Supposing you were a rock star, besides no one caring if you totally destroy your own hearing, you could put up a few hundred loud speakers, hold a Rock Concert and destroy everyone who comes' hearing too. After the Concert, while the sheriff disbands the crowd, and before the mess is cleaned up, you press the button and good-bye. You'd get a good sleep and miss the traffic jam.
A real blowout this land would support. Other than the United States Government, there is nothing around it. The mud flats could hold parking for 150,000 cars. Unfortunately, the nearest towns wouldn't survive. Susanville would be wrecked if 400,000 people drove through it. The stampede would flatten Litchfield and Ravendale. However, this county wants business, bet you could get the permits.
Since we are on permits. The underground home, wouldn't need a permit. The owner of this property has a right to build not a privilege to build. This "right" verses "by permit" has many more advantages than just what you can build. It has advantages of how you can build. You shouldn't need an EIR (Environmental Impact Report) to use an alternative waist disposal system like Santa Clara County California requires. To heck with my idea of an underground house, you want a round one, with clear geodesic Lexan dome! Ok.
Then there is the cost of the permits. What is the cost of a permit to build a 6000 square foot home in the United States' larger cities? Where I'm from it's a bit higher than $10 a square foot just for permission. Not with this place. The savings would almost pay for the land. Live in a 10,000 square foot home, and really make it a deal.
This isn't to say some bureaucrat wouldn't be there with their hand out. Ten cement truck loads would draw attention in such a small community. It would be strange to see such a large facility go in underground. They may not believe you plan on living in it. Oh well you say, so much for rights, how much to prove it's really a home?
An expression I've heard a lot lately which applies here; this place is ready for the carpenters.
The beauty of this land is its accessibility to remoteness. Simply, it would behove one to maintain the feeling of remoteness.
[an error occurred while processing this directive]