There were certain times when the airforces of WWII sent pilots to the infantry/armor battalions to act as forward observers and to call in low level air strikes.
I think units like this were present for the Allies in the Normandy landings and during the battles of the Falaise pocket, and the Luftwaffe also employed this tactic for their part in the blitzkrieg advances through both Poland and the low countries allowing the close air support that tactic demanded.
Rather than throwing smoke cannisters or having flare guns maybe there could be an icon appearing on the minimap at the location where the spotters binoculars were centred, but only while the spotter was actively selecting LMB. There must be some sort of routine that defines where the binoculars are centred because you get that for the artillery cameras.
This would have to be a specific kit within the map, and only one kit available at that rather than a selectable class, as these pilots seconded to ground troop units were very rare. This kit would have a sidearm and binoculars only.