If I were looking to accomplish this scenario I would follow Miken's example and take into consideration what Railsounds has said about speed.
I would put my LCS sensor track first, then a range of insulated rails.
I would create a custom recording that would do the following:
1. first set my momentum to low
2. set the speed of my IR equipped loco
3. set off all the horn/whistle blowing I wanted.
Setting the speed and momentum first will ensure your horn and whistle blows happen at the correct spot every time.
I would use the insulated rails to handle the lights and gates dropping. Sure this method is old school, but it makes the most sense. You can have your insulated rails start well before the crossing to make the lights go on and gate drop early. The rails can also extend beyond the crossing so the lights turn off and the gates lift after the last car has cleared.
If your trains pass in both directions use 2 sensor tracks each with own recording. 1 will handle trains going left to right, and the other trains going right to left. You could also use the 2nd sensor track (the one after the insulated rails) to set your momentum to your normal default and maybe increase speed that you are now clear of a residential area.
