I was thinking that the addition of hoard chambers could be added without a terrible amount of changes.
By using the following in game resources;
Dragon mural –
Use existing building requirements for the murals
Stack and bulk;
Biped Cloth Tent -
max stacks 10
max bulk 1200
Displayed graphic -
Hoard chambers depicted in the Dralk and Chiconis vaults.
Those ugly blanks could be made to look atractive and functional.