I glassed the firewall, even though it's probably not needed. They pinned it already as you can see from the previous picture. From my measurement, you really need 1/4" more lengthf rom the firewall for the DA50 with a 2.5" standoff to be just right (1/16" away from the cowling when the cowling is flushed against the body). I think I could've pushed the cowling in, but from my (limited) experience, that usually ends up scratching the covering on the hatch. I didn't have 1/4" ply, so I used 2 x 1/8" (not the prettiest job, but nobody is going to look in here anyway.)

On the second pic you can see the provided litght ply floor for the tank. That is NOT glued to the frame. The manual recommends putting it right next to the firewall (ala glow), but I'm going to move it back to CG. You do need to sand it just a touch to get it to fit properly. I will probably reinforce it with some triangle stock and cross grain ply.