[Jon Stratis]

You will need to be able to extend the arm to it's full extension outside the frame perimeter during inspection, and the inspector will measure it at that point (personally, I like to use a tape measure on the floor with a plumb bob to make sure I'm looking straight, when it's anywhere near close). As others said, being physically capable of further extension isn't illegal, so long as you never go that far. But your inspectors will want to see the safeguards that keep it legal in cooperation so they can tell the refs what to look for in the field so they know when it is operating legally.