The world is waking up to a new reality but it is only one of many. Other things continue as before. It takes more than one change but it's a start.
The rebuild of the Garden home page didn't need the custom walker after all. By adding a filter to
wp_list_pages() (which I remove if not logged in) I am able to run a series of
preg_replace() functions to restore the inline page deletion and section expand/collapse toggles.
The performance is far superior to running multiple nested queries so it's a big win and shouldn't be impacted too much regardless of how large the garden grows.
Update: The only snag is that I can't separate out the page delete feature and toggles so it's all or nothing. What I may do is move page deletion to the page itself, then I can have the toggle regardless of being logged in or not.