In such cases, vasilef, we can only go by the teachings in scripture. Jesus made it very clear that a man was to only have ONE wife, and for a wife, only 1 husband. This is the creation intent for marriage which He reinstituted. Jesus did not sanction for a man to have 2 or more wives. Any relationship other than with one's first wife is adultery. Many things were "tolerated" in the OT times, but those same things are no longer permissible per Jesus.
If we are to believe that polygamy is still ok/tolerated by God, because of the hardships involved with forsaking such relationships (using that as our reasoning and ignoring Jesus' teachings on one man/one woman for life), then we open the door to any illicit relationship being tolerated in the church because forsaking such relationships may be hardships on those involved.
As to the meaning of "husband of one wife" there has been much discussion on what exactly this means. I have looked at the culture of that time in the writings of the Early Church Fathers and divorce/remarriage was NOT an issue in the Gentile culture. Matter of fact, it was RARE, so I don't believe that is what it was speaking of. I also can't find evidence of polygamy being something very commonly found either.
As much as I hate to say this, I believe the RC church is right on their interpretation of that passage----that having only one wife, means that a man cannot fill such a position if he marries again AFTER the death of his covenant wife. To me, it doesn't seem "fair", yet, I understand how Paul/God wanted men in leadership that personified God...........God only has one bride for ever. In this culture of divorce/remarriage, people looking down on singleness, they have said such standards are almost impossible to fulfill.........I say, yes, probably, but in Paul's day, fulfilling such standards were not "hard".
We also have to look at this as a big picture: is it EVER ok to divorce one's covenant spouse and then marry another person? I don't believe so, so the "standard" of just the elder not being divorced/remarried does not make sense. God doesn't want ANY of His to be involved in sin, not just the elders. In the same way, if polygamy is sin, then NONE of those who name Christ should be involved in polygamy. So again, we must look at "husband of one wife" as a picture of the PERFECT image of God----who only has ONE wife---for ever. Blessings......