I think for long haul trucks if this ever works every company will want in, and want each other in. Maybe there will be some system to ensure no cheating (pay the lead truck?), but there are enough companies that run trucks that it is easy to create a convoy on the fly, with someone else, but much harder to get one for your company.
Some safety is assumed from the start. Right now such things are banned and truckers are much more likely than average to actually maintain safe following distances.
