There are precedents for this type of contract. The RAF UAS/AEF contract works on the following lines.
The company - in this case VT Aerospace - provides so many Grob Tutor aircraft on the civil register. They also provide all ground personnel required to operate the fleet at detached locations.
The aircrew are provided by the RAF and are either regular or RAFVR officers
The RAF contracts to use the aircraft for so many hours a year at such and such a cost which guarantees the company £X profit.
The aircraft all belong to VT Aerospace so the RAF saves on capital cost and the risk of keeping them "S" falls on VT Aerospace as if they don't fly they get no money. Of course if excess flying is done then VT makes more profit.
There is no reason why the SAR contract could not be run on these lines.
HF