An update to this post. John sent me the following addendum to his process for creating the ultimate maintenance CD:

You have trash (off, not onto)Retrospect and Spring Cleaning before
burning, that's what make the room for Disk Warrior. Also thinking about
it, you have to trash Disk Warrior PE as well (it's worthless). Sorry
for not including that in the original instructions. I keep a Toast
image of the custom disk handy in case, so I hadn't remade one in a while.

There you have it.