Here is a photo to illustrate. The wishbone of the first band is on the rear of three fins. This band isn't loaded since I'm afraid to do that out of the water. It would be thinner if stretched, but the two side would be pulled tight against each other. See how it would be hard to get to the two front fins with the band already loaded on the rear fin. It would help if you had a very long wishbone, but I think even a long wishbone would keep you from getting wishbones of subsequent bands down to a slot in the shaft.