We have undercarriage check lights (UCLS as we know them) at our airfield alongside the tower which can provide illumination for a night time gear / flap check etc. We also have a video camera readily available but that is more to assist the subsequent board of inquiry should it ever be needed rather than provide real time technical assistance. If there is sufficient time, we would request aircrew / engineer assistance in the tower, although as has been said already, in the majority of these cases ATc staff can indicate that gear flap etc appears to be down / up as the case may be. We also had NVG binos until last year when the inventory holder suddenly realised their replacement value and promptly removed them!