1. Don't use desktopConfig/xfceConfig, and start xmonad with the xmonadsession as you are now. If you do this you will probably need to use
ewmhDesktops to get the xfce panel to work properly.
2. Start an xfce session, but configure it to use xmonad as a window
manager. I don't know how to set this setting in xfce, but it's the