Heat peanut oil in a small saucepan over medium to 325°F. Stir together sugar, cayenne, paprika, and garlic powder in a heatproof bowl. Whisk in hot peanut oil. Set aside.
Pour canola oil to depth of 3 inches into a small Dutch oven; heat over medium to 325°F. Place halibut in a medium bowl, and pour buttermilk over halibut. Let stand 15 minutes.
Stir together flour and salt in a medium bowl. Remove halibut fillets from buttermilk, and discard buttermilk. Dredge fillets in flour mixture, shaking off any excess. Cook in hot canola oil until golden brown, crispy, and cooked through, 5 to 6 minutes. Remove fillets from oil, and gently toss in reserved sauce.
Place 1 fillet on each roll. Top evenly with pickle chips and Herbed Cream. Serve with additional pickles and Herbed Cream.