I align the edge of a shield cut feather with the offset edge of a Bitz clamp, giving me about 1" forward of the nock groove if I understand your question. This is critical to me, as I use my nose against the back of the cock fletch as a second anchor. This location may be further back than most folks, as the clamp has hash marks for aligment well ahead of that edge. At some ridiculously forward location I would guess you might sacrifice some steerage, but I don't think there'd be any problems associated with the range you're talking about.