Can a mobile pedestal substitute for a keyboard tray?

No — a mobile pedestal is a storage unit, not an ergonomic keyboard positioning tool. A proper keyboard tray mounts under the desk surface and adjusts in height, tilt, and lateral position to bring the keyboard to elbow level (approximately 1" below the elbow). A pedestal top is fixed at approximately 27"–28" and provides no angle adjustment. If ergonomic keyboard positioning is a goal, specify an articulating keyboard tray mounted to the underside of the desk surface. Call OfficeFurniture2go.com at 1-800-460-0858.