After I posted that I thought more about it and decided 4.f. didn't really apply. 4.f. is likely designed to prevent Ninjas from stealing the long jump records.

Either it's in the rules (somewhere...) or the physics of the jump doesn't lend itself toward a person rotating hands-first before landing. I would think that for maximum distance you would want to have your center of mass as far forward as possible as you approach the landing, and since your legs are more massive than your arms...

Like you, I think an Independence Weekend experiment is called for. :-)

Cheers,
Scott.
(Who is not now, and has never been, a track and field judge.)