This how I carry panels in my bag.
In the studio I take a wine cork (I like the synthetic ones best) and slice through it at 1/4" intervals until I have 4 to six little cork circles or chips. I then cut the circles into fourths. A straight razor blade works well for this.
I use 4 to 6 of these cork corners to separate 2 equal size panels. One or both could be freshly painted.
I place the panels with the wet surfaces facing one another.
This is how I store panels in the studio.
It is the same concept as the corks except I'm using strips of wood cut from excess panel material.