Sorry for the bad luck with the 3000 lately...
From my experience with 3000's (about 10 or so I have worked on). It is much better so see the battery damage on the surface, than a little damage knowing all the acid is somewhere.
The 3k mb is 3 layers, and connections and traces between the board that can't be seen are easily destroyed. 3000's with little apparent damage leakage are the most prone to failure in my travels thus far.
I have to pull my notes and schematics, but you may be able to save your clock. One time I tied the battery to a capacitor to get around the bad trace. It worked like a charm. I will have to look back to see what I did. The clock chip wasn't powered by the battery and there was no visible leads (in middle layer) so I just by passed it... I will have to see what I did again...
It's working again. The cap trimmer at VC470 was bad. The clock circuit will probably never work correctly on this Amiga again but the damage is pretty much secluded to the ground plane under the battery, it didn't even spread under Paula or Denise.