At highway speed, there will be enough ram air to cool the car.
When you say the car is running hotter than usual, how hot is it running and under what conditions?
I personally would stick with the fan clutch doing its thing, it would consume energy and create noise if the fan were on full time.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record