I hand sew my binding onto the back also and what I have been doing is sewing into the 1/4 seam area under the binding and knotting there. Then I'll start about the same place under the binding and come out from underneath so it hides my beginning and ending knots. Of course I can't finish the very last knot but I run my needle between the binding and out about an inch or two, tug a little to pull the final knot into the fabric and then chop the end of the thread. Similar to how we hide thread tails on the quilt frame.