Something centered in the truck, it is about the length of the trailer tongue, because what is in the center swings to the outside on a turn.
Off center, your long load moves closer to the inside, then across center to the outside. The further off center, the less room. Ultimately, it can be zero, because stinger plus tongue length might be short enough that you can hit the front ot the TT with the corner of your tow vehicle in a tight enough turn, particularly when backing. I know this from experience, and know I'm not the only one to do it, because I've watched other people hit their hooked up TTs when backing. I've also seen them hit the front of a fiver wit the cab of their truck.
