I'm sorry for the inconvenience, and know I'm looking like the worst forum member right now. I've been looking everywhere for a Sandbox Ghostmerging map, with the guardian's blocked off. If anyone could provide a link, It'd be greatly appreciated.
Its really easy to block the guardians by yourself, just overload the map with bajillions of tripmines and then put a tube y-intersection in front of the shooters for each tower. It will take you like ten minutes, much less time than it will take you to find a good map with it all blocked off. That is what i do personally.