A position-adjustable support assembly comprises at least one surface mount, an actuator affixed thereto, and a body coupled to and supported on the actuator free of the at least one surface mount. The body is moveable relative to the at least one surface mount in response to a motive force applied by the actuator. The actuator may be affixed to the at least one surface mount inboard of an outer perimeter defined by a frame portion of the body so as to be accommodated interstitially between the at least one surface mount and the body. In some embodiments, the support assembly may further comprise a strain gauge, coupled to the body at a terminal region thereof, which may be configured to detect a strain force acting on the body in the terminal region and control movement of the body based on the strain force detected by the strain gauge.