Has anyone running two-tank SVO experimented with thermostats?

I'm thinking to run the coolant system hotter. My system used to get to "equilibrium" on the highway at 80 degrees on the gauge but sometimes, esp. now that it's cooler out, it can stay at 60 degrees for a long time, essentially indefinitely. I don't think it does this for lack of heat, I think it has to do with the thermostat, but other than a little plumbing for the VO system I haven't gotten to know this system yet.

My goal is to switch after about 5 miles, ideally at 80 degrees, though I don't think switching at 75 or even 70 is really that awful. What temps are you guys switching at, and how many miles does it take for you to get there?

__________________
1984 300D Turbo 350K 50K WVO (two tank) "Maeby"