Miran is hilariously overqualified to be a junior officer... except that all her command experience came in the wrong uniform. She doesn't really know the Starfleet way of doing things, so.
She's hilariously overqualified- but by that same token, she is
supremely competent to serve her turn on the bridge as, say, "Lieutenant Commander Miranda, the assistant tactical officer." And of course, being very good at her job makes her a prime candidate to move up into any of the ship's senior officer slots (tactical, security, and operations being the big three) if anything happens along the journey.
Just saying.
EDIT: If she needs a backstory, we could say she's been serving on the
T'Mir. That's a known Starfleet vessel, but all its operations for the past several years have been classified, so the odds are good that:
1) Nobody aboard the
Stargazer has actually served recently on the
T'Mir, and
2) Nobody's going to question her experience as a watch-standing officer. Plus,
3) An
Oberth is probably fairly cramped and spartan, so any culture shock 'Miranda' experiences can be explained away by, oh... That, plus her being a transfer into Starfleet from some obscure colony world with weird religious views.
That's if we go through on this, which we don't have to obviously, I just wanted to be helpful and supportive of what other people might want to do.