So after a super shitty, quick and lazy install, I fished around online for the install instructions and started over.
I reminded myself that these kits have multiple parts to cover a variety of situations and that it is usual for some parts to be leftover and not installed.
With the spherical washers added to the longer end of the adapter, I was uncomfortable with the amount of bolt inserted into the fork.
Attachment 450540
I ended up using only the adapter and no washers at all.
Attachment 450541
The pads now have full contact with the new disc. Yay.