Jeff, excellent write up and thanks for the photos.
After looking at the two vids you posted regarding drilling the overload spring, I went out and checked what was underneath the Tundra. It will be interesting to see how they have engineered the kit for this truck as the overload spring rides against the main spring pack when the truck is in an unloaded state. Also, that overload spring is 5/8" thick! I guess I'll just have to wait and see what arrives.