Well, yes. But sooner or later if it hasn't already happened a sporty young woman will try to do it to impress a guy or girl as well. She may or may not be successful, and may or may not take flack for it, but she'll probably discover it's fun.
...And no, we can totally beat the Lowlands. Wouldn't surprise me if we kick the crap out of them in our next war. In all honesty, while their infantry makes me sort-of interested there's a reason heavy cavalry was mistakenly regarded as 'invincible' for centuries. And volley fire archery is just nasty even if you've got a shield. Once we've taken part of the Lowlands we won't need to trade it back and forth like the Xoh and HK do because we'll actually be building up and fortifying the interior- the reason the Lowlands are a sandtrap is nobody had a big enough population to settle it and fortify it. The HK were good at forts, but had fairly low numbers. We're numerous enough at this point and really good at colonizing and fortifying land- the nomads and Stallion Tribe area are basically hard difficulty to the Lowlands normal or easy mode and we've kept the territory we've taken.
The Trelli will be a slog if we try to conquer them- they're undoubtably incredibly rich and undoubtably have ways to translate that wealth into military power. Beating them probably requires we stop their trade route, as our Martial hero suggested, to stop the flow of wealth. To be honest, while it's a strategic enough position I'm all for subordinating them, it's probably a distant future goal and diplo-annexing may be far more practical.