Doug,
Very low oil temps can damage the engine, but 150 is probably high enough to
maintain good viscosity with Exxon Elite. The main reason you want to keep the
oil temp a bit higher is to drive out moisture that’s a product of
combustion, and that particularly condenses inside the engine after shutdown.
You can fit a remote oil door, but a simpler solution might be to adapt the way
of my old Piper Cherokee. It came with a baffle plate that fits over the oil
cooler. When the oil temps start dropping below 180 as the weather cools, I
install the plate; when it starts warming up, I take it off. My Piper part
completely blocks the cooler, but you could probably craft a plate that blocks
only part of the air flow if needed. Lots simpler than a remote oil door!
Bob P