Combine the sugar and 1 cup water in a small saucepot. Bring to a boil over medium-high heat, stirring occasionally, and cook until slightly thickened, about 10 minutes. Remove from the heat and let cool completely. (Makes about 1 cup.)
To a large pitcher, add the lime juice, orange liqueur, mezcal, orange juice and 1/4 cup simple syrup. Stir to combine. Taste and add more simple syrup if desired.
Moisten the rim of the 4 to 6 rocks glasses with a clementine wheel and then dip the rims in margarita salt. Add ice to the glasses (not the pitcher) and pour over the margarita mixture.
Garnish each drink with a clementine wheel, and serve.