That tip stall caution applies to barn door ailerons. When the ailerons are lowered as flaperons, the wing incidence is increased. If this happens only at or near the tips, that is known as wash-in and the tips will stall first.

With full span ailerons, the change in wing incidence occurs over the whole wing and the stall characteristics will not change. Full span flaperons are used on a number of successful full-scale aircraft.

The Falcon Cessna has full span ailerons and they are pretty flexible over their length as well. When you drop them as flaperons, the pressure of the airflow flexes the tip portion back up a small amount, in essence creating wash-out (relative to the center section) and helping to prevent tip stall.

I used maximum down aileron travel for the flapperons on mine, and found it to be very stable and fully controllable with full flap on landing. I used 50% flap for takeoff.

Jim