How should large table columns be handled on a responsive design?

Related to This Question, I'm interested in what I should do with a responsive design theme where the users have control over the columns which are displayed in a tabular, data rich page. Users are able to manipulate which columns are displayed, so I can't just limit the data to a few columns, as the other question's answers suggest. A potential work-around is to have a custom "mobile" query set up with pre-defined columns which I design for, but I can't control whether the users use this view or not.

Right now, I just have each column in each row stacking on top of each other and centered. I think this is not a very good design, as it wastes space and doesn't look organized. How should I best tackle this problem?

Desktop:

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Mobile View:

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