In addition to what Eric has suggested, you may also want to try reining in your highlights if you're letting them shoot off to 255.
The Epson driver will do it for you with the "Highlight Point Shift" box if don't mind the slight loss of control. If you want to remain fully in control, you can pull them back using curves in Photoshop.
Also keep in mind your final purpose for the prints. If they're going to be framed, glazed, and hung, nobody's going to be tilting the print around staring at it from odd angles (unless you have some very strange viewers), and the glazing may help reduce the problem anyway.