As a matter of fact, my engine exiting oil temperature has never exceeded the 105°C limitation, but reached it a few times in summer. (105°C was for old technology oils, today's oils can accept more)
I made some fins out of a 0,5 mm aluminum sheet and cut them to accommodate the room around the oil filter, not too close to the gascolator to avoid risks of vapor-lock and keep access to the drain.
Though there was no cool air directed onto the fins, the engine exiting oil stabilized temperature was 85°C for 20°C outside, and 95°C for 30°C: 105°C should be reach for 40°C outside.
So that makes a nice, cheap and light (a few oz) oil cooler for the hottest days of the year (just in case), easily removed when not needed.
I also added a small heatshield between the oil tank and the very close rear exhaust pipe, to avoid it radiating unneeded calories to the oil.
Gilles