All lenes project a circular image of the outside world. This image is sharpest and brightness in the center. As you examine this image, you will discover that it has reduced sharpness and it dims thus the fringes are substandard as to image quality. This is called a vignette.
As a rule, we match lenses to format size. We generally select focal length based on the corner-to-corner measure (diagonal) of the format. The 4x5 inch format has a diagonal of 5.4 inches = 160mm. in other words, a 160mm focal length lens projects an image with a circle of good definition that properly covers the entire 4x5 frame.
Lenses shorter than the diagonal are classified as wide-angle. It takes a special lens design when it comes to expanding the circle of good definition so that it adequality covers the frame size. Making a 50mm that will work with a 4x5 format would be a challenge. Making one that will accommodate a rising / falling front is likely wishful thinking.
Why the vignette? Imagine a miniature you is waking on the 4x5 frame looking up at the lens. When you are at the center of the frame, you will see a circular opening when the shutter is snapped. Now walk towards one of the corners of the frame and look up again. As you move more and more off-axis, what you see is an oval lens aperture, not a circle. This oval opening will pass less light due to the fact at it appears to have a reduced area. Thus, the further off-axis, the weaker will be the image. Additionally, all lenses have residual defects called aberrations and distortions. I fear that a 50mm on a 4x5 will have too small a circle of good definition. Now add rising and falling front and you likely entered the realm of the impossible.