To the military, marriage is marriage so long as it complies with the law where the marriage occurred.  I would expect a bit of harrassment, good natured or otherwise, due to her age.

You do have to remember that she is still a minor, and with the age difference, there is an issue as to if you would be considered violating certain sex crimes against minors.  Not all states have marriage exemption built into their criminal code and a crime of this nature could create severe issues for a military career, not to mention the your freedom.  There is also the issue there would still be restrictions on her as a minor despite the marrige, such as underage curfew.  Overall, it is a  bad idea to marry an underage individual.

My advice would be to just wait until she turns 18 and not take the risk.  Let her stay in WI until she is of legal age to marry without consent.  A few months should not make a difference.