Technically he might be able to, there's only a handful of counties that can be harvested for blue votes, and they traditionally come in late.

In a perfect world you could "harvest" 100% of votes from all the rural countries in illinios and then when millions of "late harvest" votes come from Chicago you can't count them because they'll push the voter "turnout" to above 100%.

This wont happen because the cheating is well advanced, or "ground game" networks are far more established and efficient. Also the locations favour city harvesting over rural harvesting. It's just more efficient to spend an hour harvesting 100 ballots from an apartment block then an hour driving between 12 rural farm properties for a 12 ballot harvest.