I never had an oil coooler of any type on my red supra, black one never had one for a long time, and now its only got a very small one, i did Llandow track days with no oil cooler and never had any oil temp problems.
accusump kits look a good idea to me, hold a load of extra oil and maintain oil pressure if any drops are detected.
http://www.demon-tweeks.co.uk/motorsport/oil-pumps-pressure-accumulators/accusump-electrical-oil-pressure-accumulators
I like the idea of the extended sumps, but tbh ive never had any issues with my current setup and its taken a lot of abuse in its stride, doubt i will mess with it tbh.