Or you can measure the thrust while letting the airplane slowly move forward (on a smooth surface of course), then measure the thrust while pulling the airplane backward. Split the difference for the true static thrust.
But of course the thrust generated varies as the airspeed of the airplane changes. The only time the static thrust matters is in a hover.
That's not completely accurate. It does not account for gravity which is still acing on the object.
When computing bullet energy, part of the equation is a factor to account for gravity. It would be no different here.
How many pounds of thrust does it take to overcome gravity and move the object?