[stomachmonkey]

That is one kick ass space.

I'd buy it for that alone.

Am by no means a contractor or engineer but with all that brick around can you anchor hangers in them and run stringers to lay a floor on?

I'd be a bit worried about raising the floor too much. Don't want guests falling over the wall.

Can you do gravel over the roof surface with pavers to create walking paths? I think the gravel would not upset the drainage, is easy to DIY. Could make a very Zen rock garden type of space.

Have you considered a retractable awning anchored in the back brick wall?

Lighting should be easy.