Originally I started out trying to bend the chain-stays from 3/4" tubing. Was struggling a little till I realized I had a donor frame with basically the same bends I was trying to make. After separating the existing chain-stays I sleeved and added extensions to the front and back of them. Diameters are a little different but I'll be able to blend them together later.
My welds are still looking like I'd make a better cake decorator than welder. I'm getting good penetration so I'm confident they will hold. They just don't look very pretty.
Tire and crank clearances are close to what I had drawn out. I'm using temporary tabs for the dropouts because I'm not sure of the final angle of the cantilever tubes yet. With the final dropouts I'll have the flexibility to move the tire back a little for more clearance if I need to.