--- a roof raise on that puppy would be a piece of cake! I pushed the roof on a 40' Blue Bird by 19". The Ex-Wife and I did it in two weekends. In your case, you would need access to aluminum welding capabilities but that's no biggie. Heck...go for it, now's the time!
And I have to second Shawn's rave review of SketchUp. Gotta be the coolest FREE program anywhere. Here what I did with it and I'm a Geezer...
Best part is that it's real time 3D...you can turn & rotate the drawing to see how things fit!