I think it is likely that the same teardrop used on the crab would work on two Bones (tho I have not actually tried that yet), Then as mentioned, a DMM swivel could be installed on the one teardrop. The neat thing about the Crab is its compact size. I have small bollards on the bottom friction pins (both left and right) and when unweighted, you can pull either rope away from your sides, and the Crab runs right up the ropes. Alternately, with a pulley above, you can pull your self up with one side, while the crab self advances up the other. I use the bottom arms for release, either one at a time, or both together. With a twin rope configuration (separate tips) you can move laterally, as long as the spread is not too far. (30 degrees?). This is with my 165 lbs and Tachyon rope.