Cooling is certainly a concern. With my TF spitfire, I came up with a somewhat unique solution. I pull air in from between the spinner backplate and the cowl and made a cone shaped baffle to keep the airflow across the fins. Of course, there's virtually no prop wash into the gap between the spinner and cowl, so instead of using the prop wash to blow air into the cowl, I use a small electric ducted fan to blow air out the back of the cowl thereby sucking cool air in. I've had this running with an ECS controlling the fan with a knob on the radio. I'll be modifying this to use a thermocouple sensor/controller to control the ECS. It was originally designed to operate cowl flaps.

Scott