Mounting 2nd Generation contact sensor to front door

Has anyone run into an issue mounting a 2nd generation contact sensor to the front door? My frame(may not be the correct term but referring to the area between the door and the molding around the door frame) is too deep (2 3/4") to mount a magnet/sensor on the door and another on the front of the molding. I tried mounting the magnet to the inside of the frame between the door and the molding, however the gap between the frame and door when it swings open is not wide enough, and the door hits the magnet. I thought about mounting the sensor to the bottom of the door and the magnet on the threshold but figured it would only be a matter of time before it was knocked off. Anyone else run into this issue and come up with a good solution?