I really do not understand the ole 90 degree jack for backing.
I do not think there is a pick up made that could turn sharp enough to keep up with a 90 degree jack when backing.
it could be done with the old cab over 18 wheeler i drove, but I say it is impossible and no utility do try that with a fifth wheel camper. Needles to even consider the lateral forces on the suspension.
So it looks like the slider folks rule on this post. :h
It surprises me that the stealer gave a practical response as opposed to just jumping into your pocket or at least trying to.