There is a messy way of avoiding BA fuel surcharges if flying from Brazil.
You would need to book your redemption at ba.com as 2 x one-ways to benefit from this, which means no Amex 2-4-1 vouchers can be used.
However, Million Mile Secrets misses a big point – you can book the same flight via avios.com whilst also not paying a fuel surcharge so no need to mess about with your address.
It is not fully clear if BA Executive Club is breaking Brazilian law in charging UK residents a fuel surcharge when leaving the country on a ticket starting in Brazil. Other airlines seem to think you would be, because they don’t. It is also not clear why avios.com does not add the surcharge when ba.com does!