DHCP Option 252 with port use!!
FYI you can serve the proxies address over dhcp with option 252 here and use ports with non standard port in use by your firewall. For an XBOX One this works great for getting the system to configure the proxy as the XBOX does not allow the user to manually set the proxy and uses DHCP for it.
with the standard port in use and anti-lockout enabled just use 192.168.1.1/ with your wpad files
@jonathanlee has anyone ever used served option 252 over https?