I just like to propose that the standard installation of EOS XFCE edition come with a default hotkey for opening the whisker menu. This will allow for a faster way to launch applications - as you can then just hist start typing the name of the application and press enter.
It’s done in " Settings -> Keyboard -> Application Shortcuts " then ADD, the command is " xfce4-popup-whiskermenu " and then select the hotkey to use.
My suggestion would be to use the SuperKey/WinKey
I think what @joekamprad is referring to is that it is already set up as default Alt + F1? I just tried it on my Xfce install and it works. I guess you are proposing you would like to see it as the Windows key?