Readers agree to evaluate the significance and limitations of the information provided, and accept full responsibility for the application of this information. In general, the slower you dry, the more warp you get. By drying quickly, you develop a strong stiff outside shell which resists warp caused by the interior wood. Top weights do help.
Restraints are awkward with marginal results.
Check the temperature difference between the top and bottom layers. Typically there is a large difference and this will cause more warp. The only commercial use of weights I have seen was in a mill drying 2 x 4s of southern pine. Weights do work, but their use is cumbersome in a commercial setting. When stacked in our Nyle 250, there are two stacks, end to end, each eight feet long.