You could get a wall-mounted trim piece to attach the hose. Two things that come to mind: without much of a rise in the outlet to the hose for the handheld, you could get it dribbling out that even when the divertor is not switched; and, make sure you get a vacuum breaker either built into the handheld, or on the hose. This is often sold as an in-line attachment. Other than that, finding a bracket to hold the handheld for deck mounting might be harder than a wall-mount or an adjustable bar. A bar would give you the option of using either the system as a 'normal' shower, or as a handheld.