Here are a couple of ideas that we have used to make the most of available space in our Jayco Journey.
Installed a half shelf over the wheel arch
Screwed some baskets to inside doors to add storage above low stuff on fronts of shelves
Found some great baskets to segregate and store stuff in the fridge
Replaced the En-suite curtain rail and re-positioned the curtain to opposite side.
Used the original curtain