Theoretically I wouldn't mind.
But only if I wasn't crazy in love with my DH.
When I was divorced and a single mum, I was approached with offers of entering into a plural marriage (it's religiously acceptable for us although culturally everyone is horrified). I preferred the option of being single frankly.
I could see it being an option to pool resources and have a man around when you need one. I actually know friends who have given this a lot of consideration because it was better than being a single struggling mum.
I do know of some women who are in polygamous relationships, one woman always leaves, or ends up divorced and the relationship takes the conventional monogamous status.
Also for me I would want the option of having the legal recognition and protection of being a spouse if I entered into a polygamous relationship. I wouldn't want to suddenly be homeless with kids in tow if H decided he much preferred wife two three or whatever.
I'd also want explicit acceptance and consent from the first wife. No way would I want to be breaking another woman's heart and home life (not that desperate for a bloke).
I'd much prefer to be the fun wife who H visits then goes off to his first wife who also washes his socks etc, I had an acquaintance who was the beautiful younger second wife and she had the perfect set up, her husband would come visit her and they'd have fun and then he'd go home to his first wife and second wife was happy with the freedom and lack of drudgery (no idea how first wife felt). They had a child together and the H always maintained he would take cull custody of the child if the marriage broke down. His wife never said anything about that, but I'm pretty sure reality would have given the H a shock if they ever split.
I think I would much prefer my original plan when I got divorced, which would be to live in an extended house with my best friend with both our kids, pooling our resources and talents and abilities and supporting each other bringing up our children.