After all this discussion, I still like XDMan's first advice the best.
A nice Maglight with a xenon bulb for $25 or less would be a good thing. If you can afford a pistol mounted light, you can afford a good flashlight. A 3 to 5 cell Maglight makes a great club too.
In the OP, he mentioned using the gun mounted light to look around, that means he was pointing the pistol all over the place, and not just open carrying, or keeping at low ready. What the law says we may, or may not, be able to get away with is one thing, doing what's prudent is another. If it is a thief or burglary outside, he knows exactly where you are (especially if you have a light on your pistol pointing it all over the place), but you don't know where he is. That is not good. He (they?) has the advantage This is why I think it best to stay inside until he tries to break into the house, then you know exactly where he is and can take the appropriate action to eliminate the threat.
If the same thing happens here, I'll arm myself with my .45 and a good flashlight (turned off), keep all the inside lights off, and turn on all my outside lights, while the wife calls 911. If the creep is still here when the police arrives, fine. If not, that's fine too.
It's never fun looking for bad guys when they are in a position to already have the drop on you. When I was a deputy sheriff, I've had to check buildings with alarms ringing at 0300, search peoples property for prowlers, go inside buildings with open doors, etc, and it's never comfortable - and it's always dangerous.