I think GBE requires you have the bulb on a long cord, the backup bulb bungeed and also a bulbplate and wings before you can do BIR-F, but its not all about the equipment, you have to have better skills and buddy awareness. This includes being able to hold position on the ladder with your safety glasses off and still change your bulb, deploying the long cord with other lights out and swapping to your back up bulb in case of an OOB emergency, deploying a liftbulb whilst holding position on the ladder in case you should drop you defunct bulb to prevent it from breaking and making a glassy mess on the floor, you should also be able to calculate you bulb life on the fly by averaging the wattage and voltage of the bulb and connection, respectively. Then of course you have buddy awareness and team skills to work on, making sure that guy holding the ladder up is still there, you may pass him bulb notes as needed when communicating, but of course flash your flight near him to indicate to him that you wish to converse. You dont want to change solo as that would leave you on the high platform of the ladder without buddy support should you go OOB, he can always hand you up his long cord if needed.