[pushkins]

If the ceiling is not in too bad of shape cut a hole in the wall in the room right behind the tub most big box stores carry the "Inspection Panels" they usually have two different sizes so you can cut the hole to match the size panel. Then from behind and at floor level you can see and reach all you need to repair the tub.

Nowadays it's mandatory that inspection panels are installed usually with shut off valves as well in alot of states.