On the other hand I suspect that significant fraction of the trucks are just used for commuting in flat suburbia so range will not matter.
To overcome friction, you need additional energy. The electric F150 comes with ~3.7 gal equiv. of gasoline worth of energy. The gas powered comes with ~25 gal tank.
If we assume 90% efficiency for the electric motor and 25% for the gasoline, you get:
electric F150: 3.3 gal equivalent available to move the car
gas F150: 6.25 gal equivalent available to move the car
The gas-powered stores effectively double the amount of energy, if the two cars have equal weight and aerodynamics, the gas powered will have 2ble range.
Since rock crawling is all about low end torque with guys installing two transfer cases so they can go 4 lo-lo and redline at 3 km/h I would have thought the low end torque of electric motor would be better than gas.