Rock guard airfields are REMF?
No, many airfields are so far back that the country between the forward elements and the airfields is essentially empty and available to be contested. The very potential of the RAF Regt to patrol this middle ground keeps it safe.
My daughter was in the Aux. When on exercise in the US they were treated as SF.
Incidentally the exercise was called Rolling Rock. Sense of self-humour? The yanks had an SofH too, let her drive a tank and lead a section. She got three 'kills' before her position was over run. Only because on of the US reservists had compromised the OP when he came back with some cokes!