I'm not so sure the thermostat idea will work. Some oil thermostats allow 10% of the oil to flow through the cooler even before the oil reaches temperature, then 10% to bypass the cooler after reaching temperature.
This is to avoid a thermal "shock" when the thermostat opens, and a complete loss of oil pressure in the event of a clogged cooler.
I am not sure if the 911 factory thermostat has this feature.
You could disconnect the oil lines and drain the cooler.
-------------
Chuck Moreland '86 Cab - "Sparky", '77 Targa - "Sweet Pea"