Pilgrims Don't Wear Pink by Stephanie Kate Strohm.
It's not that the cover of this book belies the content, although, technically Eighteenth-Century women wore stays rather than corsets. The protagonist, Minnesotan Libby Kelting is blonde, and she does sneak her cellphone into the bra she defiantly wears.
She has trouble cramming all the clothes she wants (including a pair of shoes to match every outfit) into her pink suitcase. And when she arrives at the interns' dorm in Camden Harbor, she discovers to her horror that when she's on the grounds, she must either wear khakis and a polo bearing the park's logo, or period garb.
Yes, this is reminiscent of Legally Blonde; Libby even compares herself to Elle Woods. Like Elle, she has hidden depths. She knows enough about the period that she's
able to teach the 8-year-old girls in the group she leads as "Education
and Interpretation Intern" how to bake gingerbread over a fire, make
lemonade from scratch, and embroider.
But Libby is still a sixteen-year-old girl, and thus prone to making mistakes like trusting the wrong people, a lesson she learns the hard way.
But, as the cover implies (this isn't really a spoiler!), the story does have a happy ending. And the book will have a sequel: Confederates Don't Wear Couture (June 2013), in which Libby joins a group of Civil War re-enactors.
FTC Full Disclosure: I borrowed this book from my local library.