i dont have clubmans, but i have clip-ons, and i'm assuming you have the same problem with the reservoir not sitting level so that with the cap off fliuid comes out.
i would suggest putting the bike on the side stand and turning the bars to the left to see if that levels out the master cylinder. if it dosent, you could just loosen and readjust the bars so that it sits level until you are done bleeding, and then readjust to where you need them.
without the MC mounted on the bars, i think it would pretty difficult to pump up the MC and hold pressure on the lever, then at the same time try to open and close your bleeder valve.