one should be enough if yer cooling system is fine.

i mounted the cooler with the brackets on the outside of the front panel, the top either needs dented in (not a wise move) or the bonnet catch cut in half, or more!.
when i done ma mates i mounted the fan on the outside cos we were runnin out of time it was booked in for a RR session, it didnt over haet in heavy traffic in the middle of summer this way. but fan in middle is prob best idea. move rad back with washers or sumitor even move the cooler forward with washers on the brackets so it sits as close to the bumper it can go.