Method for perspective matching

I hate to say it, but I have never really been successful with using Walkabout to accurately match the perspective of a view of a model to the perspective of a site photo. Sorry, Ray, but it's mostly a matter of the controls -- I find AutoCAD's Full Navigation Wheel to be far more capable, intuitive, and responsive. So here is what I do in modelspace, and it works very well.

1. Determine the proportions of the site photo image. If it is 4000x3000 pixels, it's proportions are 1.333 to 1.000.
2. Adjust the proportions of a maximized modelspace window until it has these same proportions. I adjust the width of the docked Properties and nXt palettes to do this, one on either side of the screen. I measure with a ruler right on the screen. Hi-tech, huh?
3. Create a perspective view more or less corresponding to the camera location and target. Save the view with a nice short name you won't mind typing often.
4. Use View manager to apply a background to this view, using the site photo as the background, stretched to fit. Since the proportions of the window match those of the photo, the photo will not be distorted.
5. Enable the navigation wheel with Shift-W. This enables the properties of the view, where you can set focal length, camera and target height, etc.
6. From there, use the navigation wheel's Orbit, Look, Pan, Walk, etc., as needed to get things to line up. I do not use the mouse wheel. Save the view each time you make an improvement. I usually use the X-ray visual style so I have a sense of mass in addition to being able to see key points on the underlying image.
7. When I do a final render, I usually use the same pixel size as the site photo (4000x3000). The various pieces align easily in Photoshop for post-rendering composition. I rarely use the background image as the nXt rendering background because the image quality gets degraded.

(Note that I do not use a paperspace viewport to do all this. I have found that the site photo background does not have the predictable proportions it has in modelspace. Don't know why.)

I find this method to be smooth, fast, full-screen, and free. Barring a real mathematical tool to calculate horizon lines and vanishing points, it works for me. I'd appreciate any suggestions you might have.