For the iced tea: Pour 4 cups boiling water over teabags in a heatproof pitcher and allow to brew, 3 to 5 minutes. Remove teabags and add sweetener to taste. Stir in 6 cups ice cubes until melted. Keep refrigerated until ready to use. Makes two quarts. For the chicken: Prepare an outdoor grill so that you have medium-hot heat for both direct and indirect grilling (move hot coals to just one side of the grill, or turn on only half the burners on a gas grill or under a grill pan). Once hot, brush the grill grates with oil. Pat the chicken dry and sprinkle with 1 teaspoon salt and a couple turns of pepper. Grill the chicken, skin-side up, over direct heat (the hotter side) until lightly charred, about 4 minutes. Flip and cook until faint grill marks appear on the skin, 3 to 5 minutes more. Flip again and move the chicken to the indirect side of the grill (the cooler side). Cover and cook until an instant-read thermometer inserted into the thigh registers 160 degrees F, about 40 minutes. Meanwhile, heat the 2 tablespoons oil in a medium saucepan over medium-high heat. Add the onion and cook, stirring occasionally, until softened, about 8 minutes. Add the chili powder and cook, stirring, for about 1 minute. Add the ketchup, peach preserves and 1/2 cup water and bring to a simmer. Simmer until slightly thickened, about 8 minutes. Add the pickles. Puree with an immersion blender or transfer to a blender. Set aside 1 cup of the sauce for serving. When the chicken is fully cooked, begin basting it with some of the remaining BBQ sauce and move it back to direct heat. Continue to baste it, gently flipping often, until glazed and lightly charred, about 5 minutes. Serve with the reserved BBQ sauce on the side and the iced tea. Note: When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.