I think that an order such as "ambush" would be useful- If it maintained (increased) Spotting,cover arcs and a degree of protection. and a lot of concealment.
"Hide" is intuitively the command to give, but it is too restrictive.
Ambush would be given mainly to Inf AT eg PIAT/Panzerfaust/schreck. or AT guns (and inf) lying in wait of the enemy.