Do you want to crawl up there every time? Your bed is right up against that wall, so how do you plan to reach your things?
what is the height? if find some low, two and 3 shelf bookcases/shoe shelves to put items in small containers.
Or I'd get some crate type storage, put is on wheels with a rope so you can pull the storage to you.
If you don't care what ut looks like, I'd get sone storage totes on wheels. Just to make it easier to maneuver your things.

Buy some large plastic cafeteria trays to put your boxes on. They slide easily. You can re-use them when you move. Available on amazon.

Amazing idea, thank you

@Lisa T how I've been accessing it is with a folding stole at the foot at my bed in the corner. If you look closely you can see it. I really like the idea of the shoe cubbies for smaller storage. Maybe have big bins in the back for bulky "once in a blue moon" stuff, and put a container with smaller bins up front?