Measure curve length without breaking shape apart?

I'm drafting flat patterns and need to adjust shapes until one curve of the shape is equal to a specific length.  I need to do this repeatedly.  Currently I have to break the shape apart at its nodes, select the curve of interest, view its length properties, then Ctrl-z back until the shape is whole, adjust the size of the shape, then repeat the whole process over again to see if my length is closer to the goal. 

What I need is a way to view a live curve length (length between 2 nodes along a curve) without disassembling a shape.  I haven't found a method, feature, or macro for this.  Any advice?