I just finished Peter Boag's Re-Dressing America’s Frontier Past, which is about all the men who dressed in women's clothing and all the women who dressed in men's clothing in the U.S. back in the days of the Old West.
One thing that struck me is that a lot of people cross-dressed in order to marry someone of their same sex. (They cross-dressed for a lot of other, often related, reasons too, obviously.) If a gal fell in love with another woman, she might just dress like a man and live as a man in order to marry her sweetie. If a dude wanted to marry, say, three or four handsome soldiers in his lifetime, he might live as a laundress for the 7th Calvary, for instance.
And these marriages were considered "real" marriages. People might have thought they were ridiculous — in Mrs. Nash's case, her last husband was tormented to suicide by his peers for marrying her and insisting he didn't know she was physically male — but they never seemed to doubt that those marriages were real.
I see people like David Fowler insisting on this definition of marriage they pretend is historical and therefore true. Well, if all it takes is a long history, one of the things Boag's book shows is that gay marriage has a long history in the United States.
I think it's good that we're slowly reclaiming that history instead of keeping it hidden and pretending like it didn't exist. Why shouldn't we have the same freedoms cowboys had?