In what area of camper? I use an ottoman that has a lid to store blankets in it. Doubles as a coffee table. I use baskets to hold things. An over the door shoe organizer can add lots of storage to the bathroom. Put toiletries, hairspray,hair appliances, etc in it. Keeps things handy but tidy.
Hi Darcy: Milk crates are great for storage. Also, you can put shelving under the sink, and if you can't attach it to the walls, make a shelf with 2 sides and a top and shove it where ever you need it to go. And, like Renee said, a shoe organizer is great for holding various things, even shoes! :) If you have pictures of the areas you want more storage in, that would help.
Every camper I've seen has a lot of wasted space. Look for walled areas that have nothing behind the wall or empty areas under benches. We've found and reclaimed all sorts of areas for drawers shelves and cubbies