Recon drones were used in Vietnam, so it is not unreasonable. It's just the aircraft support and miniaturization that come into question. 1980's tech is not exactly small, so the drone gets bigger and you have to support the thing. If you keep the small drone, you have to rationalize miniaturization technology that may not have existed.
I can almost accept a small, hand launched, electric propelled drone with a CCD camera, switchable IR filter, connected to a radio sending slow scan b/w video at 320 lines back at somewhere between 5-10 FPS in the size you mention. Range would be only a couple of kilometers, but you would almost have to have line of sight the whole time with it to keep it in the air. The camera feed might be a bit too low for remote flying without line of sight if the winds pick up. Such a drone would let you get eyes over a treeline or ridge without unnecessary exposure.
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