I have not strung that RQB racket, yet, but see your dilema. I Usually have problems with E-force (non Richter Tube) frames. I would use the brake and pull from the opposite side.
There are some frames that were designed without a Stringer in mind or stringing as an after thought. PK Krowning Moment is another racket that is a PITA to tie off. But I figured out a way to tie off without loosing too much tension.
Machines: Gamma 6004 2-point w/ Wise 2086 & Babolat Sensor Dual