This is what I did for my OK Joe Highland:
Works well. Temps are very even from end to end of the cook chamber. It's all 3/16 plate. Used a press brake to bend the plate next to the firebox. Drilled a lot of holes!
Probably version 3. It took a lot of experimenting to arrive at this configuration. I started out looking at the plate that Horizon sells for the OK Joe & doing a copy of that. That didn't work at all. Had 90* difference across the cook chamber.