Start importing Platinum, Diamonds, and anything you can that's valuable. With the amount of bloodshed happening here, you're going to need THE most ASTOUNDING dining hall in all of DF history, if you want to avoid tantrum spirals. Since you're going to have at least a few deaths every ambush, and you're going to have ambushes from all civs and all manner of underground nasties, then yeah, tantrum spirals will be killer.
Also, mod your entity file, where it says something like [MORAL_MAKE_TROPHY_SENTIENTS] or something like that, change it to ACCEPTABLE, and same with eating sentients. This will allow you to butcher dead creatures for skulls and bones (and meat and skin, if it's fresh) and make lovely goblin skull totems, adorned with goblin bone and goblin leather. Also might want to see about adding the little "display case" mod, it's a "workshop" created from a piece of glass, a block, and any item. This would let you put those goblin totems on display in a sort of museum of horrors, or in the killer's own bedroom. Sadly though, when crafted into a totem, the name is lost, so you can only get "Random Goblin Totem" instead of a proper name. Still, you could give your soldiers one displayed totem per 10 kills or something, so that the long-lived soldiers don't have acres of allotted killspace. Alternatively, don't add display cases, and just make a 1x1 stockpile that only accepts goblin totems.