Peter
A suggestion for the high ceiling area above the new attic-based layout ...
I presume you'll add insulation and then cover the ceiling and walls drywall. Paint the ceiling dark blue, add some wispy clouds with glow-in-the-dark paint, and string white mini-Christmas lights in random patterns to simulate starlight. Bonus feature: arrange some mini-lights in the Big Dipper configuration. Some stargazers will recognize it!
Mike Mottler LCCA 12394