I think that the challenge needs to change in order to attract more interest. Right now it's a lot of modding and work; while some people are willing to put in that effort, pure difficulty isn't always the name of the game, and it's too easy to make ridiculous levels of difficulty, especially for a fort that's only supposed to run for a single year.
I'd rather make an interesting long-term challenge; it's possible that others would be more interested too. What I've currently got in concept (not yet implemented) is an embark of dwarven heretics that I'm calling the Glass Cult. They don't use stone - all stones are modded to evaporate instantly when mined. All minerals are treated as gems instead (by this culture at least). Things are made from glass (which is allowed in Masterwork, which I'd start from) or they're not made at all. Mineral-tempered glasses result in substances similar but not quite as good as the corresponding metals, but with great effort one can make diamond crystal armor and razorglass weapons, which would sit just below adamantine. Meanwhile, since you're members of a cult, you get no migrants, no caravan, and all other races are hostile to you (add babysnatcher tag to you, remove from everyone else). The rules prohibit you from walling yourself in permanently, but with no incoming merchants, you're free to trap it up as much as you want - although you're not allowed to use any metal dropped by your fallen foes for anything but making mineral-tempered glass.
Now, would anyone else want to play THAT for a community challenge?