We used to use one of these. htt p://www.rfconcepts.co.uk/waterproof-colour-ir.htm
Made a spring attachment to go on the end of the drain rods. Also had some skids made by a drain camera company, can't remember which one. Linked to a colour portable clarity was exceptional. Still use it now after 6 years for examining voids etc, don't do stinky drains anymore.