The distance from the puck to the tool box is pretty much irrelevant. Depending on the fifthwheel you are looking at (some are now "widebodies" at 101 inches), generally you are looking at between 8 and 8.5 feet. If you turn 90 degrees, or close to it, you will need 4 to 4.25 feet in front of the pin. If you have enough bed rail clearance when hooked up the trailer may go right over top of the tool box. Provided you are not backing the trailer down hill when in a tight turn.
This video really simplifies it.
How to measure 5th wheel clearance.
