Hey Tony, great question!

I think that since the first guitar (the guitar that plays the main riff throughout) is pretty busy sounding for most of the song, what would sound really good is for the second guitarist to play single strums of the chord progression and let the chords ring out underneath. That way it adds to the foundation of the sound, but still leaves plenty of space for the main riff. Then incorporate the slide fills on top and it should be a fun approach to play.

Make sense?
Let me know how it goes!
Cheers,
Mike