The idea of using trucks to bring back the salt is an easy idea to grasp, but thoroughly ineffective and inefficient from an engineering perspective in terms of time, money, and labor. Every scenario advanced was considered and found to be lacking merit, and/or feasibility. Getting the salt is not the problem, conveyance is, and the best methodology to return it is to use the same process that extracted it. Period.
Of course, anyone wishing to buy a bag and dump on the playa is welcome to feel better about helping to restore the flats, just as long they also understand it will be inconsequential.
Building salt crust thickness requires 4 very specific steps annually: precipitation, evaporation, percolation and desiccation. Each working in harmony with the other three.
Metaphorically, it is like intake, compression, ignition and exhaust.