You don't have to remix all the sources. We are fine with one source. The aim here is to make something bad, like far from a profession studio mix. So mainly comic values, bad mixing and production. Be as loud as possible, and pick the most abrasive synths and instruments to use in your mix. We are doing this to give you the choice.
Personally i wouldn't panic, because there is a few days left anyways, and we are not taking this one as seriously as the others.
Good luck to you anyways!