If he isn't as fussed about it all, does he have the money to deal with whatever happens from some sort of neglect? If so and that is his plan, don't worry about it.
OTOH if he is standing into danger and is just too obstinate to do anything about it, you need some tact. :) ( My son is always trying to get me to use those gesture tablet gizmos which I really hate instead of my Win 7 laptop, so I can understand the "issues." :) )
I agree with Mex, first get your Australian hydrometer on those batts.
It may be possible to arrange a sort of split bank thing where he has 8 batts to use one set for equalizing while the rest run the place, and take turns to get them all done over a schedule.
