Spent most of the day monkeying around with the Highlander. Chatted with my indie about sourcing knuckles and some small bits, and he was 99% sure I was misdiagnosing the knuckle bushings. He suggested I replace the parts originally planned and then see if the knuckles do need to come out. It would mean tearing it apart again if the knuckle bushings are toast, but based on his explanation of how they should work in terms of movement and clearance, I was now leaning towards thinking I was indeed wrong about them failing.
So, I put on my work clothes and got down to business. Sure enough, once the new bits and bushings were installed, everything feels brand new! The most worn parts by far were the sway bar bushings, they were just plain dead. Otherwise, I really could have left a lot of it alone and it would have been fine for a while yet. Really high quality suspension parts from the factory, wow.
So, rear suspension rebuild project is done!
I didn't get to the oil change for the Miata, but I'm glad to have the Highlander back to full service mode.