This has been dealt with in literature by Frank Herbert in the Dune series: the fremen were a culture built entirely around the survival of the culture because their environment was so harsh (both geographically and politically, with a planetary government trying to exterminate them).
You’re taking a very harsh line, Thufferin, that I don’t think is necessary. The only reasonable prohibition I see for women in such a society is that they’re not allowed to fight in wars except as a line of last defense, in order to preserve breeders. In fact, rather than have a surplus of men, you would want a surplus of women. One man can impregnate many women, while one women can only be pregnant once at a time. As long as the man was fertile, he could make his contribution regularly. Think of it as a factory: you don’t have one machine and eighteen workers, you have one worker tending eighteen machines.
In fact, the fremen in Herbert’s novels practiced polygamy (one man, many wives) because it pinpointed infertility: if four women sleeping with the same man all fail to get pregnant, the culprit is obvious; likewise, if one woman out of those four fails to get pregnant, you know it’s her fault.
Moreover, women, pregnant or not, can handle the multitude of domestic tasks, including raising children and keeping the hearth.
As I think about it, such a culture would be much more harsh on men. You would want women to be safe and preserved, generally, since you’re preserving your capacity to breed replacements. The men have a minor contribution, and one could serve many women, so some breeding males are kept around. The rest are kept largely as warriors and for heavy lifting, and such a society would work best when the number of men competing for women was small.
The best way to accomplish a high women:men ratio would be to subject male children to intense and life threatening competition to weed out weak males and leave only very strong and warlike males around.
I’m unsure whether the men or the women would dominate such a society; I suspect the dominant role of cultural preservation would be handled by women, since they would be responsible for the daily acts of preservation and propagation. It would be a warlike, matriarchal society, much like a colony of bees.
I think the misconception that men would dominate and enslave women is a tribute to male ego, rather than an ideal of cultural preservation.
Never attribute to an -ism anything more easily explained by common, human stupidity.