Where is the best place to mount it?

 

I've mounted mine and others right by the driver's side headlight. Look at the bottom of the radiator just aft of the bumper and behind the grill and you will see various holes. Mount the sensor on one of those holes (assuming you have the original mounting tree fastener) and you should be good to go. Just put it at the side of the grill and the radiator, not directly in front of it.

 

and then for safe measures after i pushed my tree fastner in, i wrapped a zip tie around it so it wouldn't fall out...