How can I make background of an SKScene transparent so I can layer in a ZStack?

I'm trying to make a game using SwiftUI and SpriteKit. And I want to be able to layout the game in a ZStack with the game layered over the background image. In order to do that, I need to make the background of the SKScene transparent. But when I do that, the nodes that I add to the SKScene no longer show up.

Here's the coding that I'm using:

Code Block 
import SwiftUI
import SpriteKit
import GameplayKit
class GameScene: SKScene {
  
  override func didMove(to view: SKView) {
    
    view.allowsTransparency = true
    self.backgroundColor = .clear
    view.alpha = 0.0
    view.isOpaque = true
    view.backgroundColor = SKColor.clear.withAlphaComponent(0.0)
    
    if let particles = SKEmitterNode(fileNamed: "Mud") {
      particles.position.x = 512
      addChild(particles)
    }
  }
}
struct ContentView: View {
  
  var scene: SKScene {
    
    let scene = GameScene()
    scene.size = CGSize(width: 300, height: 400)
    scene.scaleMode = .fill
    
    return scene
  }
  
  var body: some View {
    ZStack {
      Image("road")
        .resizable()
        .aspectRatio(contentMode: .fill)
        .ignoresSafeArea()
      SpriteView(scene: scene)
        .ignoresSafeArea()
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity)
    }
  }
}

So the background of the SKScene is, in fact, transparent and I can see the image layered underneath it in the ZStack. But, everything else in the scene is also transparent so that I can't see the emitter effect at all.

How can I make just the background of the SKScene transparent?

Thank you.