We have added a Modify Range option to Surfaces > Multi-Surface Draft.
Selecting this option causes blue arrow manipulators to appear on the draft surfaces. Drag these arrows to modify the extent of the draft surfaces. (The arrows become yellow when selected.) You can drag the arrows all the way to the ends of the input curves.
Range of draft surface (in orange) extends from 0.25 (Start) to 0.75 (End).
You can also use the Start and End sliders instead of dragging the arrows. Setting the sliders to 0.0 and 1.0 resets the original extent.
Note: When this option is not selected (default), the draft surfaces extend to the ends of the input curves.