Since there was no mod that would work that way, I added new layer so the Heavy Bandolier item can be worn over, well, anything else, without adding new items/recipes.
Update:
On request I also added three more layers for other apparel items.
I also added compatilibity with Eltex Cape from Vanilla Expanded Psycasts so it will fit on Cape layer from my mod.
Together this mod adds/changes:
Sash layer - for Sash, Slave strap and Heavy Bandolier items
Cape layer - for Cape item
Vest layer - for royal clothing that required middle layer (vest, eltex vest, corset)
It also allows Gunlink and Hood to be worn with helmets and each other.