so my issue is that the bitfence image changes the user name and password
No, RaspberryPi StingMiner image has default username and password for raspbian lite which is pi/raspberry. First boot takes a bit of time since all required packages needs to be configured. Remote access to system is disabled intentionally by default, so if you want to configure something manually in it, keyboard and display needs to be connected directly to Pi. In most cases you dont need to do anything - just plug ethernet cable and turn the power on.
Make sure you use latest image which is located here:
https://drive.google.com/file/d/1IVnNJU_BgzFkXWrRIaQRTmcw8qVLj6PB/view?usp=sharingAnd thank you for your interest!