Polygamy has existed in America before, though that is predominately a Christian thing - Mormon to be precise. But guess after all this Religious rights carry-on, you only believe in them selectively.
People try and mud-sling with polygamy, but LGBT groups never claimed religion as their sole motivation, unlike the same sex marriage opponents who did.
So if you want or don't want polygamy, have a look at your bible and decide, as there is incest (if you forgot lot's daughters) and polygamy in there. Only gay sex is 'not condoned', even if religious cleansing/genocide, slavery, incest, and polygamy is there.
The fact something was in the Bible, does not mean that it was acceptable. Lot's daughters were a negative, not a positive. One of the validating aspects of the Bible, is that it is in fact 'real'. In a made up story, people tend to smooth over, or omit aspects considered disgusting or negative.
The Bible does not do that. Moses murdering the Egyptian for example. For the vast majority of people, if you are the hero of the book, you don't write in that you are a murderer.
So with that said....
I am convinced that there is nothing wrong with polygamy. Now that's one man, and multiple women. From everything I've read, there is no one women with multiple husbands, and several verses that indicate that would be bad.
But, nothing suggests that polygamy is a sin. Now there is TONS that suggest that polygamy is not ideal. The ideal situation is one man, one woman.
There are several stories in the Bible, like Jacob and Rachel and Leah, or Elkanah, Hannah and Penina. In both cases, and others, having multiple wives, resulted in tension in the family (imagine that). We would like to think that we can treat everyone entirely equally. But we can't. You will always love one more than the other. You'll always have a favorite between any number.
So it's not ideal, but I see nothing that suggests it's sinful or wrong.
Therefore, if there is a future battle over polygamy, I will not be fighting in it. I'd leave that alone.
That said..... I highly doubt it would be much of an issue honestly. The whole reason we have such a high divorce rate is because self-centered narcissistic people, refuse to compromise or accept the judgement of others. Do you really think the me-centered, selfish women of America, are really interested in being stuck in a house with two people they want to compromise with? And knowing one of you will be the favorite?
Call me cynical, but I don't see many American women wanting to sign that deal. I could be wrong. I don't know for sure.