A word of advice. If you take pot-shots at someone in the dark across a long distance (50yrds), even if they opened fire first, a good prosecutor will eat you alive. Proximity is a large part of "perceived mortal threat". Retreat is the only legal, appropriate response to that scenario. Carrying an AR-15 every night across your parking lot on the incredibly LONG odds that someone would attack you from a long distance will look like premediation, and a prosecutor will EASILY convince a jury that your returned fire was unjustified, let alone the fact that you were packing an AR-15, aka, ASSAULT RIFLE. This thread on the internet would also work against you, because THIS would qualify as premeditation in the eyes of the prosecution. You were carrying a "highly lethal assault weapon" and PLANNING to use it on someone...
Don't just take my word for it though. Do some research regarding people that SHOT BACK against drive by shootings. Even though they were taking fire and defending themselves, these people get charged and even convicted. Regardless of murder, or attempted murder charges, there are wreckless endangerment charges, weapons discharge charges, etc etc.
I'm not sure what your deal is, but it REALLY seems like you just want to shoot someone. Whether it's people trespassing on your new property, or breaking into your house twice a night, or a guy touching your gun in walmart, or a guy that works for your dad that just peeved you off, it REALLY seems to me like you just want to shoot someone... Not gonna work well for you in court if you ever actually DO need to justifiably defend yourself.