I've been asked to help find some sunken treasure. The treasure in this case is a prop for a large boat that was lost last fall and is worth $22,000. They already hired a guy in a boat with a sonar rig who was unsuccessful. They know "roughly" where the prop was lost but I think I may need to search a wide area around that location. The spot is about 1.5 miles offshore. I tried to die laid and use DroneDeploy but it complained that the target area was too far away from the take off area and it refused to fly. Ideally, I need a tool that will let me define a search area, and then fly the drone out there, record 4K video and then fly back for battery changes until the entire area has been covered... Does anyone know of a suitable tool for this?