Like others have said, you can do gable or you can do ridge but not both.
Have you thought abut spray foaming it? It would cost a lot but then you would not have insulation on the floor and could walk around up there and store stuff. You could also just put in a fan on gable and blowing out...
Here is my setup: http://www.grabberman.com/Media/TechnicalData/193.pdf
Here is what I wish I bought instead: https://www.metaltech.co/products/complete-scaffold-tower-with-casters/
They make stairs for the metal tech - that would be awesome.
Having said that, I can't tell you how handy it...
I have a similar setup sold by Grabber - it's got a nicer handrail setup. I've used in extensively inside building and even outside where there is level concrete.
As much as I like it, an outdoor scaffold can be setup on uneven ground and used indoors so you could have setup and use it for...
You always get more space when you stick build. Been there and done that. You don't even need a pony wall but that does let the framer use shorter sticks. My attic is huge and is framed with 24 foot long 2x12's. You also don't need a center post on a building with a 30 foot span. Run...