I have made roughly 15 glass lam bows with the inner tubes. I had heard about adding a stip on top like you mention and understand why it would be useful but I have made all 15 without the strip on top and all of the glue lines are quality, no bubbles, and no bowing up in the middle. I may just be getting lucky or am unable to see the defect but they shoot fine, look great, and don't delam. That said, my next projects will incorporate a narrow strip as part of my path toward improved bow constuction. So you might get away with it. Just be sure not to pull the inner tubes too tight or you will starve the glue joint of all of that precious epoxy.