[nvrdone]

ogre: thanks for the idea of mounting the handle parallel to the seat. That may work well.
My first thought is to mount it to the left of the seat. Then run the cable thru the floor and back to the left end of the cross rod (?). That way the cable would pull equally on both rear brakes. But with mounting the handle in front of the seat I would just have to add a pully on the left frame rail.