If you dig out the plumbing using [ u] instead of [ d], you don't need any flooring.
I've been generating throwaway fortresses to try and fix a crash bug, and I decided to give voracious cave crawlers the [CAN_LEARN] token so they'd pick up some combat skills. Like pretty much everything else, they were set to be common domestic animals, which leaves me with many interesting trade options. I also gave dwarves the ability to go without eating, drinking, sleeping, or feeling emotion, so I could speed the test up by sitting and waiting for the caravan to potentially cause a crash.
Since I had nothing to do but twiddle my thumbs as the months screamed by, I decided to murder the dwarven caraven when it came. Several scuffles later, only two dwarves remained. One was a peasant who is currently an enemy of both civ and fortress, and the other was a child who had been wandering about on the hill while everyone else killed each other.
Neither of them is the expedition leader. That honour goes to Onul Rockwiped the Alliegance of Disappearing, the former pet of some anonymous dwarf. Despite lacking [CAN_SPEAK], she has picked up a complement of social skills. I can understand how an animal can be good at consoling, intimidating, and judging intent, but conversation is a little ridiculous. Additionally, despite having nothing in her inventory, she's picked up 54 points of Armour User skill.
I don't know whose side she's on, but she's been mauling everything to death. ...Except the aforementioned lone peasant, plus a gremlin child. They're just chilling. No second dwarven caravan has come, possibly because of the merchant yaks still hanging around the site. I'll go deal with that, especially since the first caravan's items are still listed as red in the stocks screen.
Okay, it's been about a year or so, and Onul's social skills are decaying even though she has nothing to do but hang around with Unib. She still "talks" to the outpost liaison, and doesn't maul the liaison or the traders. Neither does Unib, who is fully commandable except for being ineligible for any noble posts (hey game, what do you mean, 'there are no reasonable candidates'? I have an expedition leader. I have a living dwarf. What's the problem?). If I took her out of her squad she wouldn't be allowed back in, but while she's in it she'll pick up uniform and follow orders.
Migrants were too nervous to make the journey this season, but based on Onul's thoughts about imported animals and her own offspring they're right to be wary.
This is probably all technically cheating (especially healing up Unib using DFHack), but it's so fun.