Use digital crown to adjust one value in a VStack on double tap

A project for a watchOS navigation app I'm playing with.

I have a VStack with three related pieces of text. What I want to do is allow the user to double tap in the area of the VStack and then use the digital crown to adjust a particular value in the VStack group. So far I've got the following which sets my bearing to a new heading OK but how do I link the digital crown to range value I want to change?

struct WaypointPosition: View {
  @ObservedObject var waypointManager = WaypointManager() // Where I want to go
  @ObservedObject var locationManager = LocationManager() // Where I am currently
  var bearing: String {return ("\(waypointManager.bearing)" + "º") }
  var range:   String {return ("\(waypointManager.range)"  +  "m") }
  var body: some View {
    VStack {
      Text("\(waypointManager.position)").font(.system(size: 10))
      HStack {
        Text("\(waypointManager.bearing, specifier: "%3.0f")º" ).font(.system(size: 15))
        Spacer()
        Text("\(waypointManager.range)m" ).font(.system(size: 15))
          .focusable(true)
      }
    }
    .onTapGesture(count: 2, perform: {
      // Edit Waypoint
      waypointManager.bearing = locationManager.heading // New direction
              
    })
  }
}