re: How difficult is it to install a leveling kit?

Not sure on the screws to turn to move them, google that, but you only need to worry about the vertical adjustment.

Pull your truck up close to a wall. Real close. Turn lights on. Put a line of masking tape (horizontally) right in the middle of the light beam for each light.

Back up to 20-30' from the wall. Adjust the headlights down to where the top of the beam is even with the line of tape, not above.

Done.

Easier to do this in the evening/night, for obvious reasons.