If you have to get your face and delicate wee nosie near the inspection chamber by the back door when it's all backed up, get your son to climb out the dining room window with an extension cable (yess plugged into a RCD ) and a desk fan. Place fan on wall or chair up-wind of stinky pong. Turn on full blast, direct towards face, and you will be able to happily shove your rods into the murky sludge.
Oh, and remember, if you aren't a bloke with big strong pull-the-rod-out-fast-arms, just grab the end and run down the garden as fast as you can :-)