I think you answered your question yourself.
I don't think looks make any difference to your SA. People might treat you different if you are 'good looking' I won't deny that but if you have SA you have SA. Ultimately it is what YOU think and how YOU treat yourself that makes it difficult or easy. Good looking ppl who have SA have SA no different to you.
I know from experience that looks are not the cause or solution to SA. I've been fat most of my life but slowly, from 11 to 17, managed to become average size. Even then when I was average build I still believed I was fat! People told me that I wasn't and I didn't believe them until I put weight back on and looked back at photos.
I do think looks get you more attention however, I got more girls interested in me then, well actually that was the only time in my life I've had girls interested in me! more than 2 at a time too
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. But if you have SA and don't know how to handle this attention, what do you do???
So looks are good for getting a bf or gf, but SA is the same for everyone irrelevant of looks.