It seems to me that snorkeling offers no real advantage of bridging or ferrying.   All the demonstration videos seem to have such operations taking place from prepared locations-ramps and matting laid down on the banks probably prepared bottoms.   I think that  the topographic, hydrology  and  environmental  conditions would be very restrictive in order for such an operation to be feasible.

  I would think unit of tracked armored amphibious vehicles capable of crossing and at least temporarily securing the far side until a bridge or ferry operation is established would be of more value.