While I think driver-adjustable bodywork will work well – and maybe turn out better than most people believe – I still think that there is one overwhelmingly simple solution which could create more overtaking and wouldn’t be against the spirit of f1. That would be a return to manual gearboxes (preferably manual sequential). While it might not create masses of overtaking, it would really make the difference between a driver who can maintain a perfect race and those who muck up. Can you also imagine one driver piling on the pressure to the one in front, who then makes a mistake, and so loses their place? I personally think those moments would be truly memorable!
Also not sure how much this would make a difference, but how about removing those rev counters? We saw how much trouble Button had with that at Spain, it would really mean drivers who can learn a true feel for the car would excel. If these 2 rule changes could be implemented (and would have these intended effects in the first place!) then there’d be more overtaking and driver skill would reign supreme -and isn’t that what formula 1 is all about?