C-5 pilot here, yes, chains in all cases--vans to tanks to Mk5 boat (250,000# unit load). The boat was on a trailer that had designed in landing gear to take up any slack and prevent the tires from flexing. I understand straps and agree they will work, but chains are ultimately more reliable, less prone to uneven tensioning. I can't remember how many chains went on a boat, but it was in the dozens. No rolling stock was usually put on pallets either.
GF