I simply return mine to the
fuel filter via an automotive
transmission cooler radiator, since the fuel is no longer under high pressure. It cost $100 new. but from a wreckers $20. Only in the tropics or with a very short return line would one even need a cooler. I hang mine below a beam, so it has air both sides, convection cooled.
If you get a second hand one--wash it thoroughly with a few changes of petrol and blow it dry.