Adding a cabinet to the camper may indeed solve your problem, but you may be able to get additional storage by modifying the storage space you already have. To get some ideas check out my post titled " catalog of all my mods" You can find it here
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30197633.cfm
Specifically you may be able to add shelves in existing cabinets. My link shows examples of adding shelves above the hanging rod in closets, and adding shelves in tall cabinets. I also modified the large storage space under the bed to create three drawers at the bottom while preserving some trunk space at the top.