Several factors come into play when selecting usable aircraft for this type of task.
Cargo weight will be your enemy, and drain your battery fast. I would have used a hybrid model , using gas and electric motors. This would increase your flight time drastically.
On the ground, i would have created a fleet management system , able to control several drones from a overview map.
Our member Silvio aka Super, is developing this kind of fleet management system,
I would preferably used 4G cell as communication method. This works perfect and is very reliable.