Start the chicken by mixing everything together in a small bowl, with the obvious exception of the chicken and the olive oil. Season the chicken with this mixture, rubbing all over, top and bottom, over and under the skin. Set the chicken over a wire rack sitting inside a sheet tray and stash in the fridge, uncovered, for 8 hours.
After 8 hours, let the chicken come to room temperature for an hour.
Preheat the oven to 400°.
Wipe off an liquid that's collected on the sheet trays, brush the chicken with the oil, set on the sheet tray, and roast in the preheated oven for about 45 minutes, or until the chicken registers 165° on a digital thermometer. I start checking the temperature around 35 minutes just in case—you don't want it to overcook and dry out.
When the chicken is done let it rest for 15 - 20 minutes. When it's cool enough to handle, but still warm, slice the chicken off the bone and cut into slices (something around 1/4" in thickness).
I pop the bread in the oven once the chicken comes out, or shortly after, and let it just warm through—nothing too technical. To serve, slather the inside of the bread with the basil mayo and stuff slices of the chicken, mozzarella, arugula, and your choice of tomatoes or peppers (or both). Cut the baguettes into portions and devour.
Keep in mind the mayo takes 24 hours for the basil to steep in the oil.