Bill, the temp at your trailer is what it is, unless you have the speed tech setting in the sun or let the radiant heat from blacktop get to close.This is why the trailer mounted are better because they use a fan inside to get the real conditions. I have seen the hand helds with the fan inside but it would have to be put up high to stop the radiant heat from affecting them.The heat from the engine will also affect the air into the carb and this is why you see a car pick up by sealing the carb,its cooler air.