ok so, i suggested something similar in the past, but that was during a time where the amount of effect stones were small (now we a bunch of which awesome!). personally for me, 3 headgears + 1 garment is not enought. there are so many new costumes which i would like to wear… in conjunction with what i have currently on.
it might not be possible without a lot of reworking the sprite system (i think) and adding the functionality to be able to have multiple sprites occupying the same slot, so instead, if this cannot be done automatically easily, i suggest it being implemented as a custom [Bound] headgear.
since this would be a premium feature, i also suggest it being a donation only feature (similar to premium pets)
i mean, i dont know what is possible, so maybe it can be easily implemented just with an npc that takes costumes and meshes them into one or not, but i still wanted to suggest this possibility