They may know where YOU are but they would be blinded to any other boats in the vicinity. It would also make it impossible to see your running lights which would be illegal.
The International Navigation Rules are very specific about what lights should be on your boat, when they are to be used and at what range they should be seen. If you comply with the rules you shouldn't have any problems.
Using a spot on the front is not an issue if you are only using it momentarily to see if there are any obstructions in front of you, assuming that no boats are remotely within the beam. However as there is a well defined traffic corridor on AC there's a high possibility that anyone within a mile would have their night vision blinded.
http://www.navcen.uscg.gov/mwv/navrules/rotr_online.htm