Here are a few locations with greys in the traps, but these locations would also be just as good for reds if they came by first. lol
This is the corner of a picked bean field. Grey in foreground, and red in the background. Great location for any fox.

This is a path coming out of the woods into a bean field. Great location. Set 2 or 3 traps.

This is a field path where the two field meet.

This is the same location as the double on reds in my post up above. Where a lane meets the field. All canines visit an area like this.

Woods path coming into a field. Catch reds and greys in this location.

Lane between two fields.

Corner of a picked bean field. Double on greys. Also caught several reds at this location.

Corner of bean field. Red in foreground, and grey in background.

Narrow gap between two fields. Classic location for all canines.

End of a small hedgerow between two bean fields. Grey and red double.

End of a berm at a crop change. Red.

Field corner and path.

Corner of bean field meets path.

Hope these locations help. These are good for all canines.