Same problem. Gotta keep busy over the winter. Just finished converting a storage space by the door to a clothes hamper and added a hatch to make another outside storage space above the water heater. Am in the middle of changing 36" of hanging clothes wardrobe in the head to 6 drawers and 12" of hanging space. A stereo upgrade is also in the future.
Previous projects were
Adding counter space in the galley
Butcher block top for stove
TV mount
Making a hidey hole
Wine and beer storage
Fiddles on all counters except galley
Separating the long over bed cabinet into 3 compartments
All LED lighting
Outside table that attaches to camper with adjustable legs (from paint roller handles)
Fantastic Fan
There's more. Hope this gives you some ideas for your sanity.