I'm pretty excited to see the additions. Will you have to add more support under your floor if you add length to your bench? I've been thinking about how to make my bench bigger too (yes bigger), if needed. I remember somebody on the donkey site saying I may need a bigger stove AND bigger bench so I'm keeping that in my back pocket if I need it come January. I think it would be super easy to add a extension via the cleanouts at the end of the bench.
Anyway, here's some crappy photos of my dark room that I've finally managed to get uploaded. What a process....
For my bypass, I just tapped a 6" pipe into the exhaust and then laid a small piece of mason's cloth to shape the plenum area and form that 90 into bypass. I used perlite/fire clay mix over the top of the bypass to seal in the vermiculite that I just poured into the area surrounding the bypass which flowed nicely in there to fill the spaces.
And here's the stove as it was Friday (before cleaning up the living room):
Here's the mighty fire as the fire was starting up, and the stove in action:
"Knowledge is power. Arm yourself."