Securing the archipelago before expanding the radar in Boom Beach

I’m no longer expanding the radar in Boom Beach but only defending the archipelago. Is it possible to secure the area to the point where one is no longer attacked before expanding to new areas?

It is possible to clear out the entire area of NPC and player bases, but it is extremely difficult because it will often place higher level players in your viewable area and because the fewer attacks there are in your range, the faster new attacks show up. Personally, I quickly found it was too difficult to clear out the entire area and maintain it like that before expanding, because I would often try to replace a high level opponent only to have it replaced by another high level opponent that I was unable to defeat.