I don’t have any good suggestions other than one, perhaps. And I didn’t read past the first few posts so forgive me if I missed later added info.
I would approach this not from a mansplaning angle, or a misogynist angle and more from an asshole angle.
At least in this specific example: " I’m also dealing right now with a mixed gendered group where the male boss is overriding every suggestion with his own judgement. "
While there are certainly people who dismiss women out of hand, there are also a lot of people who dismiss basically everyone, which is what it sounds like here. (Though it is possible you have the double whammy of he doesn’t listen to other people, especially women.)
Now being an asshole and a misogynist isn’t mutually exclusive, but I think if you approach it from a generic communication angle instead of male vs female, you will make him less defensive and less likely to dismiss you as something like a feminist with a chip on your shoulder (twisting it into YOU having a problem, not HIM being the problem.)
As for how to deal with it - ugh - there is not magic bullet. Because each asshole is an asshole for different reason and react in different ways to get them to behave differently. I am sure this is in those management books I never fully read. Some of them do react to humor and diffusing tactics like that. Some react well to where you stroke their ego a bit, and then suggest another option. Some are at least rational creatures, and if you can make your case out with charts and numbers, they can’t refute what you say. Still there are others who simple are god like. They do no wrong. Your problems are just because you aren’t looking at the world like he does, no one else really gets it, and so anything they suggest isn’t really important.
The one other suggest I can give is one that I learned works in general (at least for me), don’t be apologetic about your opinion. Be polite, but don’t preface what you about to say with dismissals. Something like “Hey, this may be a dumb idea”, “or maybe this is just me but” - don’t discredit yourself out of the gate. It actually primes the listener to think that the idea isn’t a good one. (Note, I still did this at the beginning of this post with out meaning to.)
I watched several videos on assertive body language and speech when I was job hunting and I think it helped me speak better in public in general.
I wish you luck. I don’t understand how assholes get put in charge so often. You may also look to HR for relief if it gets really bad.
