Combine the toasted coconut and granulated sugar and place on a small, rimmed plate. Dip the tops of your Collins glasses in the simple syrup and then onto the coconut and sugar combo to coat the rims with coconut. Set aside as you prepare the drinks.
In a cocktail shaker, combine the mint leaves, lime and lemon juices, the simple syrup, the seltzer water, coconut milk and rum. Shake in the cocktail shaker until the mojito is very cold, about 30-45 seconds. Strain into the 2 Collins glasses and garnish with more fresh mint.
