Rear mount radiator?

The biggest problem to solve is always how to run the coolant lines back. Inside the passenger compartment is a bad idea with any soft lines; you could get badly scalded if anything goes wrong. Hard lines inside.....maybe, but underneath would be best if there is room. I would look at how the offroad trucks with rear rads do it as an example.

On a related note....I went through some international rally rules some year back and noted that they prohibited running coolant through the roll cage....so that trick has been tried! Crazy....