Nice design/set up! There probably won't be much interior pitch at a span of only 30ft for scissor truss. Would that pitch even be enough of a gain for your lift to justify the scissor truss? Did you consider doing 14ft sidewall and "standard" truss design. It would be easier to insulate, apply ceiling coverings on your own and provide a much better lighting pattern with less shadowing with a straight ceiling. Especially with all of the fine motor work, detail work etc. you may be performing.
Also, I'd highly suggest increasing your window sizes or at least adding a few on the porch side where you'll have your view/hang-out area. The more natural light, the better. If you need the wall space, maybe even consider a "piano" style window much higher since you have a 12ft sidewall. I have 46' wide garage with 14' side wall and I have three 18"x 8ft windows at the 12ft height purely for natural light. No loss of usable wall space, they are great!
