Leave the single-pivot on the back. That Shimano brake you tried to link (always leave a space on each side of the link) is easily good enough to lock up the rear.

If you throw a dual-pivot on the back you have to use too fine a touch to avoid skids; it's worse than pointless extra metal.

Definitely prescribe one for the front though. It's how you do stoppies on a road bike.

Also, +1 lose the turkey wings. If you want bartop braking, use interrupters. But bear in mind they require extra skill to set up properly. Those guidonnets look cool (never seen em before!) but I think an aero lever plus interrupter is a better idea overall...