As far as I remember Leia never took the Skywalker Name. In the EU it was always listed as Leia Organa Solo.
Its a good theory and one that would fit..... but is sad that no matter what Mara can't be brought into canon since they made Luke a bitter old coot who never got married.
I've read the books, I know she went by Organa Solo. I just like to add Skywalker to her name personally, if only because while she rejected Anakin as her father for a long while she never rejected her brother.
And it is sad, Mara deserved better, but considering what they've done to Luke without a second thought, I'd rather Mara stay in the EU than be brought into canon.