Will be interesting. Some additional passive cooling to the oilpan will help, but not as much as actual cooler will. If you're not fond of the extra volume with the long lines and large core of an air cooler, you coud also look at an oil:water exchanger like some of the race teams have used. e.g.
complete-oil-coolers-ecd54 - oil-coolers - The Laminova heat exchangers - Laminova