In Northern California permission to build almost anything comes at a significant cost. Both in terms of the time it takes to prepare materials for review (such as plan documents for the site, septic, building, fire, etc with County officials), as well as fees. I don’t want to scare you but it can cost $30,000 in fees for a new home that is under 2,000 square feet. I don’t know the cost for the Mueller Road Project yet but I did pay $1,505 for just a preliminary design review. This will take 4-6 weeks and is required because the site is in a scenic area. So no pink doors or purple roofs!
Contact me and I will share an example of the documents you will need. Of course your specific needs will vary but you will get a good idea of the effort required.