The shorter the fifth wheel, the more difficult it gets. It's like backing up one of those little box trailers X2. My little 22' fiver gave me fits trying to back it into my cramped shop. I just about wore the gearshift out going back and forth. I could get a 38' boat in there with no problem, first time, every time.
One thing that I found that helped me out when I got my first fifth wheel was to move the slider hitch to thmaneuverre position. This moves the pivot point aft of the truck's rear axle and makes it more like backing up a regular trailer.
After some practice, I have no problems backing my 28' fifth into campsites.