Hi Bogan ,
This is the sort of thing Darren was talking about.
https://arcpanel.com.au/roof-systems...m-roof-system/
There's plenty of companies around but its not that cheap. The best thing is its span capabilities.
I built my beach observatory with something similar but never quite finished it (typical builders house!!!).
I used a quick steel frame, screwed the panels on, and then rendered it with acrylic render.
The roof panels just slide apart on rails with no wheels (not finished)
The roof could do with some colourbond but its still waterproof.
These panels cost me about $80 each for 2500x1200x75 with acrylic both sides.
My wife thought it looked a little bare so she got a bit artistic.
My new obs will be similar but bigger and finished
Just a few ideas maybe.
Cheers
Andy