Personally I find the sweetness from the triple sec enough, and so omitted the agave syrup. However, I tried to bring in the agave flavour by reducing the mezcal to half of that recommended and making it up with Almave non-alcoholic blue agave spirit. Could perhaps amend this to 3:1 in favour of mezcal next time, but I really enjoyed the result.
Made this with 7.5 ml of ginger switchel as was lacking a liqueur -- fiery but invigorating; probably 5 ml would be better, but still very tasty and refreshing.