I have a 5 and a half foot bed. I thought I would need to put the 5th wheel hitch an inch or two behind the axel. As it turned out, my hitch is correctly installed over the axel.
I have no issues driving turning or backing. On a tight turn (very unusual) I have to watch out for the scamp
hitting the cab. This gets close on backing in tight situations.
My 1988 5th wheel needed a new axel a few years ago, when I replaced it, I had the shop raise the scamp an extra few inches. To make up for the new vehicle bed height.
Hope this helps...
Also, fun project, I had the shop extend back bumper and add diamond screen.
For more storage space and NEW rear stabilizing supports.