Since your Carrier isnt supported.

Youd rather go to /private/var/mobile/Library/Carrier Bundle.bundle/
(Its a shortcut to your Carrier Bundle in use.

This is with your SIM inside.

This way, youll find out which Carrier Bundle to edit.

Change the Default_CARRIER_*********.png and FSO_CARRIER_**********.png..
Use a size of your liking. Id recommend 70x20ish.