As far as making another model I don't see why it would be impossible, I think those who said that probably mean getting it added into the game along side with what we have already. A lot of content from the game is within grasp for most to diddle around. "Hacking" can easily be a word tossed around easily however.
Personally I am not into meshing but there's a few great modders out there that has been playing around with the game and they'd probably know a thing or two over the years they've been playing around with the game. I'd suggest getting in contact with Tigg, Thierry or Ruby1234 if possible since they might know something that can help you set it up if even possible. I know I'd turn to them first if I ever wanted to figure something out with meshes. Who knows maybe they'll see this thread and get in contact with you or have already.
What Red said really. Hi. Ruby1234 here.
Making your own character model isn't necessarily "hacking," as it's something I've messed around with as well. At first I thought it couldn't be done but then I realised what I was missing... I should be able to release a mod that I got permission from KovuLKD to release once I get off my butt and finish it. The main issue is usually within the adding a new slot to the character creator, and also it being kind of rude to just add a new species to someone else's game like that.
That aside. The way the item system works, it already has a sort of, "built-in armature." Items already move with whatever bone you assign them to. So that's not the issue. The problem is that the items are ignorant of the character model, a result of the lack of collisions within the game. Since there are no character model collisions, the items will just go wherever the bone tells them they're going, (just by literally being clamped the bone, as the armature would, and rotating with said bone howevermany degrees on whichever axis/axes) and will clip through whatever's in the way. You can assign them an armature all you want, but it won't change anything.
I'd say it's not really possible to add collisions like that into FH unless you've got the source in your back pocket, which I'm sure many of us coders/modelers wish we did. It might be possible to clamp collisions to the character models through a bit of work, but getting them to be mobile would be another thing, since even the game's Object Maker doesn't support animations. But still it'd be a bit rude to "hack," or make any sort of major edits to someone else's game without asking them.
Nothing's impossible, but there are limits to be aware of.