You really can't paint the front fenders different, and if you had the truck green & the rear fenders black it would look like you had a green truck with a pair of new e-coat fenders that didn't get painted.
The only way they came 2 tone that I know of is the roof white & the body a separate color, or the roof & upper section of doors & upper back panel white & separate body color.
If you really have your mind set on 2 tone, try
THIS