Cha-cha-chá comping — Scivales's Ex. 45, the pattern he says fits "Guantanamera" and countless other tunes, moved from D to C (I IV | V IV). The cha-cha is the slow, square relative of the mambo: medium tempo, danced on the beat, every part "in the pocket".
The rhythm is a conversation between the hands. Right hand: a chord on beat 1 and a short repeat on the and-of-1, then the same on beat 3. Bass (and the pianist's left hand in the original): octaves on beat 2 and the and-of-2, beat 4 and the and-of-4. So something is always sounding on every beat and every "and", but hands never collide — that interlock is the cha-cha feel, and the güiro's "cha-cha-chá" sits on 4-and-1.
How it sits on the clave: 2-3; nothing is anticipated across the bar line, which is why the style feels so grounded next to the son montuno.
Practice: keep the repeated eighths very short and light; the weight is on the bass octaves. Try the same hand-to-hand rhythm on any I–IV–V tune.