Also to note, this is the same WiFi Tether for Root Users app mentioned in the OP. Just change the settings mentioned in fryguy2's post. Again, thank you!
I am with T-mobile and I'm not sure if this works for MetroPCS users. I did notice that once I got it working there was no up-sale screen at all. Strange. Every page worked just fine. Weird. However, T-mobile does only give me a small amount of Mobile Hotspot with my plan so I still need to mask the headers to hide any desktop data. No problem with Fiddler.
EDIT: Not sure if this method will work for everyone! I just tried using the native T-mobile hotspot app (which never worked before today) and it works fine for me now. So take my case and add a grain of salt if it works for you too. Not sure what happened. I am not paying for extra Hotspot access. Not sure if this method somehow unlocked something or if the T-mobile system somehow missed me today and will catch me tomorrow. We will see.