They should make a Brute kit for the 4 door JK. Shouldnt be to hard and not nearly as detailed as the TJ kit because we already have the wheel base. Just remove the back seat and door frames. Get body panels to cover the 2nd row doors, end the cab right behind the driver compartment where the roll bar is and make have a drop tail gate instead of a swing out.
I would buy the kit! only after I paid off the JK though...