1. the lines have to be bigger because of line loss.
2. make sure the lines cannot be crushed by a jack, etc. and out of the path of rocks thrown up by wheels.
3. the cooler definitely does know it's not in front of the car - because it's out of the airstream.
4. even with a fan: does the moving air under the car (generated by car speed) go in the same direction as the fan (increase), or the opposite direction (decrease)? You may to move it around somewhat.
5. is the hot air exit area between the cooler fins and the bodywork at least as large as the total of exposed fin area? Example: 10" × 10" cooler is 100 square inches. For all 4 sides bleeding air, each one must be 25 sq. in. area, and if 10" long must be 2.5" away from the panel. If only 3 sides are exposed (1 ends at a panel), they must be 100" ÷ 3 = 33", or 3.3" away, etc. If the air enters on the body side it should be 25-50% larger.
6. hot air rises - if the fan is below it should push, etc.