I know you had another long thread before about similar stuff but you'll have to excuse my bad memory with how all of that went before... I'm still not entirely certain why you aren't able to use a state preset on your item's FirstPersonPerspectiveItem that adjusts its position offset, e.g. during the "Aim" state. Maybe you already explained this in the last thread, so forgive me if that's the case! But generally speaking you should be able to just use a state preset that forces the item's position offset to whatever value you want. And then if there are cases where states conflict with each other and whatnot you can use state blocking to force a particular state preset to be active/inactive at a certain time, etc.
Also, as a side point, GameObject.Find is not a reliable way to get a reference to an object when there are likely other objects with the same name in the scene (which I think I even saw in your hierarchy that there are). So I'd just use an inspector reference like you're already doing.