Oh right, those guys were around. Getting their help would probably be our best course of action- seeing as the tub was a metal rectangular box, it probably won't do much other than get in the way and make water drain a little more slowly. We'll need something that actually covers the whole hole.
Meiling could probably move a boulder or something (or maybe that mossy rock if it's not stuck in the ground too stubbornly), but other than her, those random youkai we passed sound like our best bet.