You are correct Isaias, I have done the same thing (but used Apache instead of IIS).
Since the port 8000 is already used by IIS/Apache, WebD cannot use the same. Perform the redirect at IIS/Apache at some other port and make use of it, if you need to use WebD.
This is kind of weird thing (Apache/IIS + WebD) but we have a requirement where we need to use WebD in any case, so this is the only approach coz WebD alone cannot redirect & host the UI files. For hosting we need either IIS or Apache. 