I don't really have an answer for you. I would love it if someday, Lexi could have full run of the house - when we are home, first, and then, when we are away.
What I might do is start with one room. Go for a short period of time, and see how it goes. Extend the time you are gone gradually. If that goes well, add a 2nd room, starting with a short time, and gradually increasing it. Continue until she is able to be in the house for the period of time you are usually gone.
Good luck, and let us know if you find something that works for you!