The golden rule of trailering is to NEVER under any circumstances go between the truck and trailer, nor step across the hitch of a bumper-pull --- NEVER.
Always go around, either around the front of the truck, or around the rear of the trailer.
I have personally knocked three people down by them shortcutting between my truck and trailer --- me moving really slow and no one badly hurt any more than them looking like an
idiot --- ; twice while sitting in line at a stock-yards, and once at the loading chute at the veterinarians.
In all three cases, I heard them squall and immediately stopped.
In the neighboring town, there is a court-house square with roads entering from four directions, with pedestrian cross-walks.
Some years ago, a guy with a big load of cattle eased up past the cross-walk and stopped for a second; if you could actually see this place, you would understand why; just as he stopped rolling, this
woman of about 40 short-cutted
between his truck/trailer and he took off, killing her dead.
A year or two later, at the very same place, I just happened to see in my side-glass, from the corner of my eye, this
woman and two little kids do my truck/trailer likewise; thank goodness I saw her and sat still.
After that, I threatened to put slack chains between the truck and trailer that would prevent any future such happenings.
If you never let yourself acquire the habit of darting between the truck/trailer, you will never be likely to do so at the wrong moment.