Thanks for both suggestions. Wayne, I think you were correct. My W, H, orientation and check box "Rotate to Fit" confused me, the driver and the printer. I went back and looked at what the proper settings have been for me for other prints on custom sized paper on my 3800, and I duplicated those for this new print/paper size. It printed correctly this time. For whatever it is worth, here they are:
Page Setup: 12"Wx30"H custom paper size, image placed in landscape orientation @ 100%
Image Settings in LR: 28"W x 10"H horiz pano image, no "Image Settings" boxes checked, Layout 0.13 margins, Page Grid 1x1, Cell Size H=10", W=28"
With these settings, the screen preview of the printed image looked correct. Loaded the 12"W end into the printer and it printed correctly.
Thanks again guys.
Brad