For the more inventive souls among us, here's an alternative to your current oil tank. I'm not sure of your existing tank size, but I did have to make adjustments to get what I thought would be worth while results.
This technology is common among automatic transmission performance guys, an oil pan with linear mounted cooling tubes.
Take a look below. The capacity is listed and if the tank is too large in diameter, maybe it could be lengthened to gain a bit more room and still hold the same amount of oil.
And for those that may be so inclined, a person could mount a 2-speed blower motor from a car heater and mount to one end of the tank so it's enclosed/sealed. Then duct the exhaust out through a 4" flex tube and with a simple diverter butterfly valve, you could have heat on for the cabin. If not wanted, leave the diverted to exhaust outside.
Just throwing out options.
After seeing the hard work in yobtaf's post above, this would seem to be child's play.
I believe that done with care, the tube could be sweat soldered into the end caps prior to welding on the outside tube and fittings. The tubes I'm figuring would be rigid .5" copper tubing. They solder very easily and are more than durable enough for the job at hand.
