I would suggest a new way of doing it.
Why don't we create what would effectively be a new armed force.
Basically we remove SAR from the RN/RAF. Remove the Air Ambulances from the CAA. Contract the whole thing to whoever wants to supply aircraft, engineers and aircrew.
The aircrew(as I am aircrew I'll concentrate on them) can then be made up of current serving mil pilopts, current serving civ pilots. They would all get paid the same.
the aircraft would be provided by a contractor and placed onto the miliary register(much like DHFS). This would then allow low flying, it would also not be necessary to worry about sizes of landing sites etc, as you can get away with more in the mil. NVG tasks could be done better.
training can be provided for ab-initio at DHFS/SARTU and then onto the new force for conversion for whatever type they go to fly, be it small Air Amb type things or larger SAR type things. Pilots/crews would have the flex to change between the various types and so on.
The whole shebang could be funded by DoT, MOD and charity so no-one would have to have a massive contribution. The best bit is that the new force could control it's spending and get what it wanted and not what the mil say.