We are just finishing the work on our cabin. We are very happy with Mark Williams, who lives in Murphys but has done work in the area for years. Typically builds one major project a year, and our cabin happened to be it last year. We poured a concrete floor underneath the cabin and had extensive foundation work to to in the same area. Sounds similar to what you have in mind.
He is prompt, very reliable, and extremely reasonable with high quality work. Very easy to work with. It is a small operation he runs by himself, but you will not be disappointed. At the very least I suggest you give him a call at 209 728 8404 or his email is
suncreekfillmore@hotmail.com