We often load our bikes on frozen lakes, when not riding we wrap the wheels with carpet/heavy duty canvas liners to prevent dulling the screws we use when ice racing, they look a little like tire warmers. A set of tires runs $800 and the truck box would dull the screws without liners and the screws would destroy the truck bed. There is NO traction for the tires and very little for boots, even the bed of the truck is slippery. Surprisingly, despite effectively turning our wheels into chainsaws then riding them on ice, most injuries occur loading the bikes.
I mounted a cheap 1500 lb ATV winch to the front box rail on the truck and hook the cable to a foot peg. Slow, controlled loading made easy.