As silly as it may sound, I often find the most opportune thing to do with these small caliber anti tank guns is to just hide them in the corner and hope they enemy finds them equally harmless and leaves them alone. Unless of course there are light armor around.
Scenario VCs (not to mention initiative) often are impacted by step losses, and these things are especially vulnerable due to their column shifts.
1st edition PZG 45mm's didnt even have a direct fire value at all for what its worth. You would sometimes still be dragging those by wagon to the front to fight an infantry v infantry engagement
Cynicism aside, I have found them handy to plop down with the motorpool in the back areas to prevent armored cars from poaching trucks when the scenario rewards doing so.
While not specifically mentioned, the German 75mm IG appears similarly useless, but its range actually makes it useful in interdicting disorganized Soviet forces. Not so much from the combat results of a 4 values shot likely on the 2 column due to range, but from forcing all the movement of the Soviet INF to be combat movement while under its sights. Short on leaders, this impacts the Soviets somewhat often.
Just my rambling thoughts. Do with them what you will.