Bring a small pot of water to a boil and fill a medium bowl with ice water. Cut a shallow X in the bottom of each peach and plunge it into the boiling water for 30 seconds. Transfer the peaches to the ice water to cool. Peel the peaches and cut them into 1/2-inch wedges; reserve the peach skins and pits. Transfer the peaches to a bowl and toss with the lemon juice. Cover the peaches and refrigerate.
In a medium saucepan, combine the cream and milk. Add the vanilla bean and seeds and peach skins and pits and bring to a simmer. Cover and remove from the heat. Let steep for 20 minutes. Strain the infused cream into a bowl.
In a medium bowl, whisk the egg yolks with the sugar and salt. Whisk in half of the infused cream, then transfer the mixture to the saucepan, along with the remaining cream. Cook over moderate heat, stirring constantly with a wooden spoon, until slightly thickened and an instant-read thermometer inserted in the custard registers 165°, about 5 minutes. Immediately strain the custard into a clean bowl and stir in the maple syrup and bourbon. Refrigerate the custard until chilled, about 30 minutes.
In a blender, puree the peaches with 1 cup of the custard until smooth. Transfer the pureed peaches and the remaining custard to an ice cream maker and freeze according to the manufacturer's instructions. Transfer the ice cream to a plastic container. Press a sheet of plastic wrap directly onto the surface and freeze until firm, about 1 hour.