You need to control both harbors for that though. If you have a crew, they can make the transaction with another organisation and you don't need any local resources.
Even if you don't use an actual harbor but just a "harbor", you need control of that area or someone you sell the drugs to needs to have that control.
You also need people that put money on the drone. No point in shipping the drugs, if you don't have a way to transport the proceeds into the other direction.