I worry that with the foldable windshield of a CJ, you might end up "warping" it when it's unsupported by a hard top. Even with a soft top I wonder if THAT is enough support for someone to put their weight into a grab handle.
If you go forward with this idea you may want to put that handle as low as practicable. Personally, I'd reconsider.
Be kind. If for no other reason, it will confuse the daylights out of people and make them wonder what you're up to. And ALWAYS drink upstream of the herd!