Hi Quinn,
I have 4 credit cards. I changed 2 over to my then preferred name. I had a letter from my therapist just in case. I was never asked. I llegally changed my name then the other two cards. 
If someone did not accept a CC I planned to just take out the other CC in my then legal name. 
My bank account was a real PIA to change. Other than that it was just show my decree ( give them a copy, stamped so get extra) and fill out the form. 
My W Fargo CC was changed via verbal request. 
This stinks, when you start out with a new name you have 0 credit until it is established. I guess there is a way to link the two names but the peeps at the credit reporting agencies are less than helpful.