I also fly an RV-7A with an IO-360 and the Vans oil cooler in the standard location on the engine. I'm based in SoCal. I also had to add an antisplat oil cooler shutter to keep the temperatures high enough in March. In the summer, I occasionally see the oil temperatures above 200 in climb with the shutter wired wide open, but they stay below 200 in cruise.
I added the shutter after starting Phase 1, so I decided against putting another hole in the firewall for a shutter control cable. So far, my engine has been happy with the shutter in place but safety wired in the maximum open position. But if I were earlier in the build, I would have added the antisplat control cable system for more flexibility.
David