was it moved over as far toward the zipper as it would go? if so, maybe cutting the corner off the pad would allow you to slide it even farther toward the zipper, or some kind of shaping to allow you to move the side over a bit more. since it goes in diagonal, the corner hits the side of the hammock and the pad stops even though the side of the pad is not quite to the edge.
my 41" wide uq seems plenty wide, and have not had any complaints about it being too narrow. it is mobile so it can be positioned right where you need it though. a fixed quilt might need to be wider.