Very nice. As you no doubt concluded, the geometry of the rack and lower arm is all wrong. After a string alignment, I made a jig to measure bumpsteer and used a Baer kit to adjust it. I was able to reduce but not entirely eliminate bumpsteer at all compressions. I did all this during the build and so don't know how it would have driven, but I find it to be very predictable. It tracks well in hard corners with bumps and at high speeds. Your solution is much more comprehensive for sure. Getting the pivot points to line up eliminates most of the BS without the bandaids that I put on it.

Ed