It's great to meet you Stranger, and it will be interesting if we end up discussing some of your other views such as non-violence at some point, you have clearly put a lot of thought into many things.
In relation to polygamy: I believe it is not prohibited in the Bible though I am inclined to the perspective (possibly just by upbringing) that monogamy may be the ideal.
It is entirely reasonable that you incline to this perspective from your upbringing. Most of us start with that understanding. We then should critically examine that understanding to determine whether it is valid or not.
If we are to define something as "ideal", there's a very strong argument that the ideal is celibacy, given that Paul within scripture itself states very clearly that celibacy is better than marriage for those who are called to it, and any marriage has the potential to distract us from our relationship with God. To argue for either monogamy or polygamy being ideal you'd have to argue against Paul, and I'm not going to try that.
I think it's better to consider the whole idea of "ideal" as being a red herring.
God has plans for all of us. Those plans are different. Celibacy, monogamy and polygamy are all permitted, all have both benefits and disadvantages, and all will be God's plan for somebody. In fact, at different times in life, all three might be in His plan for you!
And what is ideal is doing God's will, whatever that may be.
What I mean by "ideal" is that which most closely models the relationship of Christ and the Church. I think that the self sacrificial nature of Christ in relation to the church is better modeled by a husband in monogamous marriage to one wife but also suppose that submission of the wife to the husband as the church as to Christ might be better modeled by a wife allowing for her husband to be in committed marrital relationships with women other than herself.
Again, this is where most of us start. And this comes from our focus on the "Church" as a singular individual.
That emphasis is a heresy of the Catholic church, that the Protestant churches have not yet shaken off. The heresy of Catholicism is saying "the Church is the one bride of Christ, headed by the Pope, and to be saved you have to be in the one true Church". This is a heretical understanding that has been adopted in order for one individual in Rome to assume control of all Christians.
Interestingly, monogamy is also Roman culture, was adopted by the Catholic church from Rome, and was ultimately imposed on scripture and mandated for Christians by the Catholic church. The early church actually included some polygamists, because they were mostly Jews initially and Jewish culture was polygamous. Monogamy and Catholicism go hand in hand.
Yes, the church is sometimes spoken of as a singular entity - but the Greek word for Church refers to a group of individuals, not really a singular thing. Even when spoken as a singular the word used is one that emphasises that it is made of many individuals.
The emphasis in scripture is rather that all of us, as individuals, have an individual relationship with Christ. We can approach Him individually and without any mediator. We are all, individually, united with Him.
The Protestant reformers recognised that this was the crucial error of Catholicism and brought people out of that church into individual relationships with Christ. Protestantism rightly emphasises our individual relationships with Him - but has largely retained the monogamous terminology and imagery of Catholicism, and continued to prohibit polygamy.
A number of early reformers saw through this and realised polygamy was acceptable. Martin Luther said he could not condemn polygamy, and actually authorised a polygamous marriage. Associates of Luther wrote to King Henry VIII of England advising him to become a polygamist rather than divorce his wife, because that would be preferable. Some early reformers actually went so far as to take multiple wives - one of the Wesley's sisters actually married a polygamist! This history is covered up by the church, as this was a step too far for most people to be comfortable with.
However, an acceptance of polygamy is both the starting condition of Christianity, and the natural result of the reformation returning to that starting condition.