You know, since in this premise the Captain is not someone we see all the time, we can go with a more elaborate alien makeup as well as an atypical actor for television--perhaps someone with greater prestige who'd be okay with a recurring role but whose schedule doesn't allow for full time?
Now that we see guys like Kevin Spacey and James Spader doing television, I'm not completely sure I know what "an atypical actor for television" really is anymore... but if one is to have an alien captain, someone who'd be fun to see in alien make-up and would be a badass leader is Nicole Kidman.
(Or perhaps more realistically, Claudia Black.
Some interesting ideas on the Pinterest board. I'm warming to the great-(great-great-great) grand-niece of Kirk notion as patterned on Jennifer Lawrence, whom I love, and I like Ensign V'Kree, too.