Well after enjoying a lazy Sunday morning, I got to work on the dog platform. First thing was to notch out the corregations so the flat portions would lie atop the longeron flange.

I found that the gusset creates some interference here...

...so I just trimmed the corner off.

Next step was to cut this half (actually slightly more than half) to line up with the center support. I also trimmed the corregations away so it would lie flat on the center support.

The other half went much faster since I knew what I was doing. After seeing how this fits in, I don't like that supports are visible through the areas where I trimmed away the corregations. I'm thinking of adding a doubler strip along the edges to cover that up. We'll see.