I wasn't implying to copy Greg's design (or any other)- though he and I are great friends, live a few miles apart and wheeled all over Co and Ut together. His bumper is straight across like your original design. The taper is just a preference I would like to see. Also, Greg's side tapers down towards the wheel well, while I would prefer to stay straight/level as you have shown. The D-II is 10" longer behind the rear wheel, so different issues all together.
Lastly, the bumper could end at the vertical seam of the rear quarter panel, mimicking the factory look a little closer- for my taste/use anyway.
One last thing would be to nix the factory hitch, and integrate a receiver into the bumper. Sadly the orig hitch is welded to the frame, but we have removed them numerous times. Some sort of attachment to the frame would likely be advised if you like this idea.
Thanks for fielding the ideas- may be interested in a couple bumpers pending final design and tire carrier. One for my Eco Challenge Disco, and one for the '99.
PM info/pricing/etc if you prefer.
Cheers!!