I'm not suggesting anything, only a few hints to help
It's against my interest of
promoting Polish vehicles
, but there is one possible slot - an usage of 859 Schlepper C7(p) tractor was really insignificant, and probably limited to rear units in Poland. Around 150 were built in Poland, I don't know how many the Germans took.
As for SdKfz 254, surprisingly, according to Jentz they seemed quite widespread - 128 were made and they were used in artillery regiments of several armoured divisions, along with SdKfz 253. First were made in June 1940. Photo pm27682. However, I don't know if it makes sense to add another AOP vehicle, especially, that max speed on tracks was only 20 km/h, while on wheels it wouldn't be off-road.
There were only 10 6-rad and 58 4-rad SdKfz 247 armoured staff cars made, used in headquarters of Aufkl.Abt (meant to be only one in a company) and Kradschutzen Bat. No fixed armament, no radio set [Jentz].
Most typical of forgotten German vehicles seems French Unic P107 tractor, used in some units as gun tractor (and the French made some 2000 of them). There is a photo already pm27669.
https://en.wikipedia.org/wiki/P107
http://www.autogallery.org.ru/m/unicp107.htm
There were also several gepanzerte funnies upon its chassis, but they were less typical.