I have a better recommendation for a fix of the thermost this weekend.
Drain 1-2 gallons of coolant from radiator into a clean container.
While the coolant drains...
Disconnect 3/8-inch coolant return line from coolant degas bottle and move out of way.
Disconnect cold-side CAC tube from intake elbow.
Loosen lower connection of cold-side CAC tube at intercooler and rotate out of way.
Remove upper radiator hose.
Remove old thermostat (two bolts...save the housing for the next time you flush...easier!).
Install new thermostat.
Install upper radiator hose.
Install 3/8-inch return line.
Refill radiator through the coolant degas bottle using captured coolant.
This won't take long...a little longer that it takes to fashion a cardboard radiator cover and reprogram the Insight perhaps but with better results for a 2,800-mile trip.
The thermostat is readily available online or at Ford or many auto stores:
[RT-1169]Motorcraft Thermostat-RT1169-Ford Diesel Trucks - Diesel Filters,Additives,brake rotors, and brake pads for Chevy, Dodge and Ford Diesel Trucks
Overnight shipping is steep of course so I'd check out the local Ford dealer or auto store if you don't want to spend big bucks for delivery.
A properly functioning thermostat begins to open at 192F and is fully open at 219F (they are stamped 89-104C) so a temperature below 190F is usually not a warmed up engine...or it is REALLY cold outside.