I believe that projector has vertical
lens shift (see Page E-28 in the manual). This should let you mount the projector over a pretty wide vertical range and then shift the image vertically without having keystone issues. FWIW, Page E-29 of the Sharp XG-V10XU manual references adjusting both the lens shift and keystone, as the projector supposedly does provide digital keystone correction.
A projector lift is certainly a possibility, but don't expect it to be inexpensive.
You could also look at something like the Silicon Optix Image Anyplace
http://www.siliconoptix.com/products...x/anyplace.cfm . This lets you manipulate the signal to correct for geometric issues in the display.
Many newer projectors, especially those intended for professional applications, have both vertical and horizontal lens shift capability. One warning on consumer AV products, their warranties often specifically exclude commercial or professional use, something to consider if you have to have a valid warranty as part of the purchase. So read the warranty statement or limit the choices to equipment intended for the application.