Set your estate to production and prepare yourself for regular policework. It shouldn't be that hard if you are diligent. With level 2+ walls, a unit of 100+ archers or (even better) MI should be able to manage against almost anything monsterish, unless it comes in the form of multiple units.
As for boredom, hey - people play solo strategy games all the time. Plus, people might show up to join you, you never know.
