When changing wing incidence for roll control, it is important to have equal but opposite deflections on both sides. Otherwise you will add load factors to the results of your roll inputs. If you have some gearing which will couple the movements of the two wing halves, the idea works. But try to avoid a stall; stalling has a high potential to result in an uncommanded roll.
Next, make sure that the lengthwise center of gravity location of each wing is as near to the hinge of the wing as possible. If you have some distance between the two, any roll input will add inertial moments around the hinge. This will make your stick come alive in a rolling maneuver, in unpleasant ways. If the center of gravity is behind the hinge, roll accelerations will cause amplifying moments. Your stick will move into the roll if you accelerate fast enough! Conversely, if the center of gravity is ahead of the hinge, every roll acceleration will be damped by inertial moments around the hinge. Much safer, but will cause more stick forces than necessary to achieve a good roll acceleration.
If the hinge is close to the aerodynamic center of the wing, control forces should be low (except for friction, which might be immense in case of poor design). To move the wing by a servo tab, however, adds one more degree of freedom and is an invitation for flutter. It might work, but is best tried in a second step. Only make sure that the hinge is ahead of the aerodynamic center, or the wing will not return to neutral with zero force on the stick.
Unfortunately, a stalled wing has a much lower suction peak at its nose and less pressure recovery in the region of separated flow, so its center of pressure moves back. In an unsymmetrical stall, the stalled wing will pitch down and will pull the unstalled wing into its positive stops, stalling it in the process and resulting in an uncommanded roll input.
Structurally, there is no problem if you use this on a small plane. Many designs have used tubular spars, so use one smaller one which sticks out of the center wing and two bigger ones in the outer wings which will slide over the center tube. Adding two needle bearings on each side with enough spacing should lower friction enough to make the wings move even under load.
Historically, the Akaflieg Berlin 02 "Teufelchen" used a similar way of roll control. The inner wing was conventional, using two box spars and a stiff nose covered with plywood. The outer wing was fully fabric covered and had its ribs movably fitted to a tubular spar. By twisting the outermost rib, the outer wing could be warped for roll control.
Three other aircraft with a fixed center wing and all-moving wingtips were the Granger Archaeopteryx, the Short SB.1 glider and the Short SB.4 Sherpa research aircraft. All were built once only. Please follow the last link for pictures of the control surfaces in action.