Substitutes:

• Dark Rum: For this drink, you can use any kind of dark rum you like and even experiment with a blend of rum of your choice. If you don't have any dark rum on hand, you can substitute light rum or bourbon. The flavor profile will change slightly but still makes a decent cocktail.
• Sweet Vermouth: Dry vermouth can be used instead of sweet vermouth if needed. Just add a small splash of simple syrup to balance out the bitterness. You can use any kind of red or sweet vermouth you have available on hand for this cocktail. You could also try a fortified wine like ruby port or sherry (Oloroso, Palo Cortado, or Pedro Ximenez for example) for a different flavor profile.
• Angostura orange bitters: Angostura bitters or any type of spiced bitters can be used as a substitute if you're out of orange bitters. It will give the cocktail a different flavor, but still tasty. Lemon bitters could also work, in which case we recommend garnishing the drink with a lemon zest instead of an orange zest. If it pairs well with your rum, you can even experiment with a dash of cocoa bitters!

Making a Pitcher of Palmetto Cocktail:

• Scale: To make a pitcher that serves 8, multiply all the ingredients by 8. That would be 12 oz of dark rum, 12 oz of sweet vermouth, and 16 dashes of orange bitters.
• Mix: In a large pitcher, combine the dark rum, sweet vermouth, and orange bitters. Add ice and stir well.
• Serve: Strain to remove the ice, serve immediately into chilled cocktail glasses, and garnish with orange zests. If you have some leftovers, be sure to keep them in the fridge (make sure no ice cubes are left inside) in an airtight container as vermouth is prone to oxidation when kept at room temperature.

Making it Non-Alcoholic:

• Dark Rum Substitute: Use a non-alcoholic dark rum substitute; these are available in the market and do a good job mimicking the flavor of dark rum. If you’re feeling crafty, you can also make your own dark rum substitute by infusing together rooibos tea and a bunch of spices of your liking (vanilla, cinnamon, clove, allspice and banana are always a good way to start). Mix all the ingredients together, add hot water, cover, and let it infuse for at least 3h (the stronger the better, so if you have time let it infuse overnight. In that case, you can either let it rest in the fridge once the liquid has cooled down). Give it a taste, adjust the spice level if necessary, and strain it once you’re happy with the result. Stored properly (in an airtight container in the fridge), this “tea-rum” can be kept for up to a week.
• Sweet Vermouth Substitute: Opt for a non-alcoholic sweet vermouth substitute. You can also try using non-alcoholic red wine, in which case you’ll probably need to add a bit of sugar to the final drink. To recreate the spiciness of the vermouth, you can add a dash of Angostura bitter to the wine. 
• Orange bitters substitute: To get the citrusy touch brought by the Orange bitter, you can slightly muddle an orange zest into the shaker/mixing glass before adding the rest of the ingredients. Also, note that 2 dashes of bitter in an otherwise alcohol-free drink won’t raise the overall ABV of the drink. The drink will indeed chemically contain a drop of alcohol, but won’t make you intoxicated at all. Depending on your reason for not drinking alcohol, this can also be a suitable option.
• Proceed As Usual: Use those non-alcoholic substitutes instead of the regular dark rum and sweet vermouth, follow the original steps, and enjoy a non-alcoholic Palmetto cocktail.

Making it Vegan: