I had originally hoped that I could do something a bit lower on the b-pillar and still get some decent triangulation, but as I studied it more it just became obvious that anything else would be more "cosmetic" than functional
As I've already stated, each bar I add is a real struggle between safety/functionality and convenience/useability. Fortunately, I think there is very little else about the remaining cage layout that will require concessions like these two new bars did.
An interesting note: With so many bars meeting at a single cage "node", I actually realized that there were some fishmouths that were about to be hidden under the newest bars....unwelded! I had to carefully trace the new bar outlines onto the intersection point, then remove them and finish-weld the stuff that was about to be buried underneath. Then, I could add the new diagonals and tack them into place. It's a little like a chess game...you have to plan your moves ahead of time to avoid getting trapped later on.