As far as I remember, composite helicopter blades (as an example) use a metallic mesh in the skin construction and the whole assembly has a metal bonding strap to equalise any electrical charge between the head and blades. I was in a Puma in 1980 travelling from Natuna Island at night to Singapore with a medevac, when we built up St Elmos fire.
An interesting 'scenic' experience, when the electricity discharged from the helicopter, it was like looking down a cheap torch beam, brighter at the edges than the centre. Maybe I have digressed a bit, but yes the designers will certainly have thought it out as its a problem that has been known about for years.