In most instances you can obtain a temporary structure permit for the purposes of a job site/security quarters while you're building your permanent residence. However, I'm not aware of any county in the State that will allow you to live in any home that does not have a Certificate of Occupancy aka CO.
You may be able to get away with a self-contained RV or trailer but I think you'd run into a few stumbling blocks if you tried to obtain permits for a manufactured home unless it met all the other permit, set up and installation requirements. I think a composting toilet would be completely out of the question. Perhaps a portable toilet at best (outhouse with a regular pumping service.
But bottom line you need to check with your local building and planning department before you do anything. If you just decided to move in without addressing permit and planning issues you could be red tagged and forced to move the manufactured home.
I'd also be concerned about the year of the MH. Many if not most building jurisdictions have some pretty stringent zoning rules and regulations addressing the age and condition of the home. Just be very careful before you pull the trigger and start spending a lot of money. You may be wise to check with a local MH dealer near you and explain your situation with them. They should be able to give you some pretty good information. Good Luck.