A friend and I we recently did build a board bow with a backing. We both did build the same bow except for the backing. I used a wooden backing and my friend used a clear glas of 0.04. Before we could apply the backing we glued on the riser, then we tillered the bows until both limbs bend even. After that we are ready for the glue up. Don't forget to cover the glas with masking tape to prevent scratching the glas. We glued the backing with standard epoxy ( type L ) wrapped it with plastic foil and fixed it in a mild reflex-form. Use enough epoxy and wrap the plastic foil really tight to make shure you get good glue lines.
Glueing the reflex into the bow
After the glue up you have to retiller to get your desired draw weight, because the backing adds a couple pounds. To cut the glas my friend used an angle grinder with a carbon disc. After that he used a belt sander to get the limbs into the final form.
Cleaned after the glue up
My friend tillered his bow to 60@28 and mine ended up with 50@28. Unfortunately I don't have more pictures because I didn't plan to do a build along.