Piano reduction of a string quartet

[avanchnzel]

I'm meeting a flautist tomorrow to try the last two movements of Mozart's Flute Quartet in D major. As you can see from the title I'm replacing a string quartet. We've performed the first movement in public already, and I barely got by with all the thirds and the most awkward counterpoint I've ever played on a piano.
The finale is a nightmare of repeated notes, stretches and huge jumps along with the thirds and horrible counterpoint. I can do those at quite a tick but honestly, the required tempo is 140. I have to play consecutive thirds and repeated notes. In semiquavers.
This flautist is going to pay for my carpal tunnel surgery.
The accompaniment is really quite a work of art itself and would have been lovely to play at about half the tempo, but that's not what should happen in the original. I'm not exactly Martha Argerich, so would anyone have any ideas on what to do without completely rewriting the accompaniment in a more pianistic way (and thus losing the character of the piece)?

[keypeg]

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[avanchnzel]

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