Place water, honey, lime juice, chili powder and cayenne pepper in a small saucepan over medium heat and cook for just a couple minutes, until the honey has dissolved completely. Remove from heat and place in the fridge to cool.
Once cool, add simple syrup to a high speed blender along with coconut milk, frozen mango, and tequila. Blend until smooth. Taste for extra lime juice, if needed.
Place all ingredients for salt rim in a shallow dish and mix to combine. Use a lime to squeeze around the edge of four 8-ouce glasses then dip them into the salt mixture. Pour margarita mix into those 4 salt-rimmed glasses. Garnish with chunks of mango and coconut and lime wedge on the side!