Some bikes (dual-sports, like DRZ 400 and KLR 650) have the starter use a one-way clutch behind the ignition/alternator rotor. Unloading these bikes (and maybe others) using the clutch to slow the roll back can lead to a bike that won't start...won't even turn over, even with jumper cables. Voice of experience...had to "run and bump" to break it free - then it started fine.
That being said, I think the Harley has a typical "bendix spring" starter and doesn't have the jamming issue.
I agree that if you do use the clutch to slow your descent, put the trans in low gear so it's unlikely to turn the motor backwards.
My biggest problem loading/un-loading my GL 1800 into Toy-Hauler is at the bottom of the ramp...inseam challenged! Loading, I just go for it...un-loading, I use the reverse and turn the bars to the left as I approach the bottom of the ramp so my left leg can "touch"!
