I would have to see the holes.. Might be best to leave them.. Logic:
If the batteries should leak any acid mix onto the tray.. Path to ground where it will dissipate harmlessly (in the quanity you have there) as opposed to making a mess of things.
Every time I have installed a plastic battery box, it had a hole in the bottom... I put it there with my drill.. WHy, See above.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times