Looking at your diagram I am impressed you can fit all that in your van! About the only option for making everything fit while you sleep would be to somehow suspend some gear from the roof.... Even then...
As far as cold food goes.
- Salads (potato, pasta, lettuce)
- Sandwiches; make the toppings ahead of time and stack all the servings together separated by wax paper. Assemble the final sandwich with condiments at the last minute.
- Cold soups (gazpacho?)
- Soups can be kept warm for 12 hours or more in a vacuum thermos. Warm tomato or chicken soup goes well with a lite sandwich or bagel.
- Pre-sliced fruit can be tossed into a salad with a sweet/sour dressing. Finish up with some nuts.
- There are lots of dry foods which can be made in minutes with hot water. Get a jet-boil and you can have food with zero setup in less than 10 minutes. Oatmeal, dry soups, instant rice etc.