Great thoughts, @Randy, I always appreciate your thoughtful replies. A couple of quick reflections:
I have absolutely no issue with a person holding an Egalitarian position and/or that Eph 5:21ff is based on cultural assumptions that are not binding today. I think the arguments are very strong, I simply find the classical complementarian position more convincing. However, I would never teach that it is sinful or unbiblical to hold to an Egalitarian form of marriage. Each must do what is right by their own conscience on this point.
As to Pauls teaching of slaves and masters. Slavery is absolutely wrong, no doubt. And yet Paul also addresses Children and Parents, a role relationship that continues in the present day. Additionally, much of what Paul says to slaves and slave owners are applicable to employers and employees today too. But I freely admit this is probably my weakest point.
I think that whether complementarian or egalitarian, Christian marriage should promote mutual flourishing. In our case, I stepped down from my employed church ministry and leadership roles so my wife could take up a job as a seminary professor. I now work part-time for a charity and do most of the housework/childcare. Too often Christians have used Eph 5:21ff and complementarian to prop up ungodly sexist gender tropes.
This leads to my final reflection. I would agree that Paul is working within his cultural presumptions, but I would suggest that he does that in a counter-cultural way. For men, Greco-Roman culture was about power, status, and influence. If Paul wanted to work within those cultural norms we might expect him to say that husbands should care for their wives as a good king cares for his people, with wisdom, dignity, and thought to their welfare. Instead, Paul invokes the image of a slave washing and preparing her mistress for her wedding day. There is not a lot of power, status, and influence to be drawn from seeing oneself as a slave whose ‘job’ is to serve their wife. In that sense, I don’t think Paul is making the best of the cultural situation but rather trying to replace it with a better vision.
I say all that not to convince you that I am right and you are wrong, but only to help explain my position and, hopefully, lessen the struggle.