Based upon "seeing combat" in squadron strength..............and based upon this being by far the worlds most produced aircraft there should (IMO) be only one plane considered for observational duties................
The U-2 later known as the Po-2
Classed as a vehicle it could be available from GV fields

and we could include the WW1 damage model
U-2LSh: Two-seat ground-attack, close-support aircraft. The aircraft were armed with one 7.62 mm (0.30 in) ShKAS machine-gun in the rear cockpit. It could also carry up to 120 kg (265 lb) of bombs and four RS-82 rockets. Also known as the U-2VOM-1.
U-2LNB: Soviet Air Force night attack version, built from 1942. Armed with one 7.62 mm (0.30 in) ShKAS, plus up to 250 kg of bombs under the wings for land support. Earlier aircraft were converted to improvised bombers from 1941