This mod does a couple of things. Firstly, it adds the ability to add a chest to any dragon. Secondly, it adds an inventory GUI that's color-matched to the dragon.

A couple of notes: because Dragon Mounts: Legacy uses Shift+RightClick to make the dragon sit, and I use the same keys to apply a chest when not in the inventory screen, to make the dragon sit when it has a chest, you'll need a bone in your hand. Additionally, if you remove the saddle while mounted, it won't kick you off the dragon, but you won't be able to control them.

ENJOY! -Ainz