My thoughts are that you should find an eviction attorney to handle this for you. You may have options that you are not even aware of. It might be a good idea to add up the amount of money it has cost you to own the property since May plus all of your time spent on this, then keep adding it up for however long the attorney tells you it will take to get them out. I dont even file the notice myself, I pay extra and have the attorney do that. I believe what you want is an attorney that specializes in eviction only. At the links at this site there is a great orange county attorney Steves Silverstein who covers a pretty wide area.
Good luck, please keep me posted.