What size should each sprite be in my spritesheet for a customizable character?

So I have a game where the player can customize the character by equipping armour and such. A popular approach I've seen is to have a naked character, like so, and animating each piece of armour or item in a separate sprite.

My dilemma is that the additional items may be outside of the bounds of the original character. And I assumed that it'd be easier to position an item from a 64x64 image onto the character, which his also drawn on a 64x64 image. So every sprite added onto the character would be the same size and the 64x64 sprites would all line up with one another. But that obviously means that I'd be wasting a lot of space on the spritesheet. The other option would be to use as much space as the item uses in the sprite, but with all of the equipment, it'll look like a jumbled mess of assets of different sizes on the character.

I'm very new to this, and I wasn't sure what to do.