I have fitted a false back to one of the backrests in the cabin. This gives just enough room for a few A2 sized charts to be slid in behind the seat. I have had the charts laminated at a local print shop so they should be fairly indestructible.
I have built up two simple little book shelves on the forward cabin shelf. I had fitted an MDF base to the shelf a year ago, and the bookshelf sides are just screwed to it. They will only hold a few, but that is all I carry. I carefully masked all round the wood so that I could oil it without staining the MDF. Finished the job by knocking over the bottle of linseed oil, sending it flying over everything. So much for preparation.