AmaxB, You are quite the DIYer. You can buy AR15 lower receivers that are 80%complete and finish them yourself. The jig will cost about 80-100 and the lowers are about 40 to 60. You can also save money by building your own upper. No registration, no serial numbers... and all legal. You could spend another 100 and get a Slide Fire stock to make your AR full auto... again.. all legal.
But
Home defense surrounded by woods. Yeah it sounds like a shotgun would more suit your purposes though.
Now, for home defense I look at it this way. For an outside perimeter scenario: Everybody and his brother own a semi auto rifle. If bad guys were to approach your house it would be.. they go bang bang, you go bang bang, etc etc. But if they go bang bang.. and you go full auto bangbangbangbang they would high tail it out of there and go look for easier prey.
For me: a Semi auto rifle (AR or AK) for outside defense. For inside defense: A 45 caliber pistol (Colt Model 1911 or Glock Model 36) . A shotgun for general purpose work.