Stephanie and Elizabeth are the two I thought of before reading your list. (One Beth that I know, I only found out was a Bethany not an Elizabeth when I was best man at her wedding!)
Assuming it's understood the objective here is to come up with inconvenient names rather than good ones, how about Bough? As well as "beth" and "boff" sounding very similar you'd get the benefit of nobody knowing how to pronounce the name in the first place. That it's normally a surname or nickname would also add to the confusion!
Or Bathory? Bethany and Bathory are pretty similar. As a bonus, people would wonder whether you'd named your kid after the Blood Countess
or a prominent black metal band
. It would certainly stand her in good stead if she wanted to be a goth. (-8
Or go for a different kind of confusing similarity: al-Eizariya