Some WIP photos from new part I started to work with, it does need quite a bit of work still, also that is not necessarily final angle as sides still need cutting and attaching to make angle right, but it is starting to form from there.
Rear diffuser angle is bit difficult one, I try to start with as close to zero degrees as possible, hopefully I can make it adjustable so that I can make changes to it relatively easy way.
I still haven't really thought much of how to make diffuser, but it might be same material as this Kamm, does not weight too much and when attached well should stay well on place. 0.5mm galvanized sheet metal, which means that I need to make some parts to make it bit less flexible for the Kamm at least, for diffuser, I think there is enough places to attach it so that it is not flapping etc.