Temporary Shelving

Many of you with a 1999 Damon Daybreak know that the storage does not amount to much so we are trying to decide on the options we may have.
Here are a couple of photos of the cabinets in the slide. There is an indented area in the cabinet that is for the window coverings.
The bottom shelf is pretty narrow and the top shelf is not much deeper.
You can see an extension that makes the top shelf to the full depth of the cabinet.
We will do this in three quarters of the 2 cabinets for now.
This is something that we are doing until we can see if it will work okay for us. We will make the shelves  from a permanent material once we know it suits our needs.