IMO, the best way to achieve results would have been to not send troops, but to pay top dollar for the farmers' opiate supplies. Poppies are the highest value crop they can grow, and if the farmers are making money, the whole community is happier, healthier, better educated, richer, and they don't need to rely on the Taleban. Indeed, given the Taleban are anti-Poppy Farming, the farmers would fight back. The West could use the poppies medically, give free heroin to addicts to avoid 'fix money' crimes, or simply destroy them.
EDIT: plus you cut the criminal gangs and traffickers out of the equation!
Are they anti-poppy, I thought that was where most of their funding came from?