I'm planning a sliding door to cut the airflow through the
strake mounted ducts, so it probably won't matter.  I can get the temps
up quickly on either one.  But I still think the oil will get hotter
faster than the water.

Although it can be very uncomfortable, you can save a runaway over temp by turning on the cabin heater full blast. Might even save your bacon. If you have the muffler sleeve style heater no such option exists. Plus the monoxide threat is much reduced.

 

Lynn E. Hanover