Whats in the SOP's is up to the FOI in the country that's the AOC is held. Per say it is not illegal to fly CAT in class G.
For you to get a change in that you need to convince EASA to change EU ops.
Biz jets only have SOP's if they are operated off an AOC if they are private then there is nothing unless they want there to be something.
Get a slot and the boss wants to get to Biggin from Inverness. Cancel IFR down the A9 transit through GLA airspace through the Manchester Low level corridor and skirt round the London TMA to get in all at 249 knts. Perfectly legal
Absolutely nothing the airprox board can do anything about.