destinationsky
......and I would speculate that you already have the required survey data, if you want a safety case speak to NATS they would dearly like to keep their contract.
As far as mitigation goes, you have Class D airspace, a luxury that GA aerodromes in Class G airspace/ bandit country do not have. Should be a walk in the park with the generic Safety Cases that are available.
Provide the procedure and the customers will fit the kit.