Online Community of Zenith Builders and Flyers
Have you used an endoscope for inspections, yet? A half inch hole and pop in plug for the snake and you are in business. I purchased one this winter and am still finding new uses for it. Sometimes it’s great, sometimes it may be easier to remove some rivets.
HomeBuiltAirplanes.com recently had a write-up on spar theory that may help you understand the impact of adding the extension. The author appeared to be very knowledgeable, but subject is over my head.