I have been messing around with PS system upgrades for big tire trucks, and armored vehicles. I have learned some hard lessons relying upon stock cooler set ups.
Here are some set ups I have come up with:
Aux cooler on a 91 using a toyota made cooler off a Lexus of some sort. Inline filter also in use up stream from cooler. Mounted behind ARB bumper.
Cooler off vehicle:
Mounting method. I welded nuts into core support. But Nut-serts are also great option. Use rubber grommets! They help tremendously with cutting down on vibrations and increase life cycle.