2 cups mango-flavored rum (such as Malibu®)
1/2 jalapeno pepper, coarsely chopped, or more to taste
2 cups orange-peach-mango juice (such as Dole®)
3 tablespoons orange-flavored liqueur (such as Grand Marnier® or Cointreau®), or to taste
1 1/2 limes, juiced
4 thin slices jalapeno pepper
Combine mango-flavored rum and chopped jalapeno pepper in a large glass container. Let infuse, at least 1 hour. Strain out jalapeno pepper and discard.
Mix infused rum with orange-peach-mango juice, orange-flavored liqueur, and lime juice together in a bowl.
Fill a cocktail shaker with ice and add rum mixture, working in batches. Cover shaker and shake until outside of the cocktail shaker is frosted; pour into serving glasses. Garnish with jalapeno pepper slices.