Mount above and strait in front of you in the cab using bungie cords; tilt down at your head.
You might have to drill a hole or 2 in the base of the fan stand
Dewalt also makes one.
Fill gallon milk jugs 3/4 full with water and freeze overnight.
Keep them in a cooler with 2 inches of water at the bottom and 2 soaked towels.
One jug is for drinking. The other to keep the water at the bottom of the cooler cold.
Take out a soaked towel and wrap around your head/neck, yes your hair will be wet.
When it gets warm switch out with the other towel.