It sounds like there is just too much distance between the standards for that lens. A 65 is a really short lens for most 4x5's, and you may need a recessed board to focus at reasonable distances. Does the camera have a standard bellows or a bag bellows on it? If it's a standard bellows it probably cannot collapse enough for infinity focus for that lens.

Keep in mind that to go from your current focus distance of 1 M, to something farther away, the lens needs to move toward the film plane.
Unless it's a retro-focus design, at infinity, the lens will be sharp when its nodal point (more or less where the iris is) is 65mm from the film plane. How far away is it now, with the standards as close together as possible?