The reason this is so challenging is that no matter how you do it, there will always be a weak link in your chain of locking.
If you lock the stick/pedals, then the control rods and cables will endure the loads the control surfaces encounter from winds and attempt to pass on into the control system as they are designed to.
If you lock the surfaces, the rods and cables are safe, but now you're locking some fairly fragile aluminum surfaces to nearby surfaces which are only marginally stronger. If the locks on the surfaces are made larger, the loads will be diffused over larger areas, but then you've ended up with larger and perhaps heavier and more cumbersome locking pads.
Now, if only someone would create rotating tie-down pads, so the plane could weathervane into the breeze at all times!