Used to practice it with 2 mixers/4 decks a fair bit and have played out a few times like that.

We always did it with one mixer having it's output going into one channel on the other mixer. So, the guy who was playing on the main mixer would play two tracks with a third channel available with one or two tracks playing.

As we got better we'd mix it up more and try some different stuff. I think my advice would be not to try and play to many tracks at once. Think about what the overall sound is like and don't just throw them in. It's tempting to play 4 (5 or even 6) tracks at once but it generally sounds shit unless you really get it right. Record some sets to see what it sounds like and take it from there.