Id personally would love a ferret for that body plan.Idk about the stoat honestly. While it would be a cool and fresh new animal, it really is super tiny, smaller than meerkats even. And it doesnt even have the advantage of being kept in large groups to make up for it.
If were talking about something more traditional weasle like i think the yellow throated marten really is the best there is. (although it wouldnt really suit a tundra pack, unless its expanded to also include taiga animals)
Many different color morphs, super common in zoos, culturally interesting, cute and the only carnivoran that could reasonable come in a domestic pack
Id see them as an absolute win