Make simple syrup: Combine sugar and water and a small saucepan. Bring to a simmer and stir until sugar is dissolved; let cool.
In a large container, stir together chilled syrup with lemon juice, rosé, brandy, tangerine or orange juice, Campari, and lemon, tangerine or orange, and lime. Chill until cold.
Garnish with fresh mint, if desired, and pack in a travel pitcher. Serve over ice, topped with seltzer.