I could not read dimensions on your sketch, sorry, but if it is drawn to scale and each run is truly only a bit larger than the coop, if you only used one run at a time) it's already non-ample run space for just 12 chickens, I'd be concerned about 25 feeling quite crowded.
It would be a good idea to set two additional posts so that none of your runs have narrow acute corners (as they all do in the upper right and upper left corners of the layout right now)... those corners are just *asking* for trouble in various ways, including but not limited to chicken A cornering chicken B there and administering a severe clock-cleaning.
Another possibility might be to make the periphery of the run all the same distance from the coop, and then make up one or two moveable panels that could be attached at different points to cordon them off from some of the pverall run space. Since it doesn't take all that much to keep chickens in (as opposed to keeping predators out) this would not need to be heavy duty or cumbersome; and would give you more flexibility as to how and where to divide the runs for rotational purposes.
Honestly though, with those small areas, I'm not sure how much it's really going to be WORTH trying to rotate runs and replant with cover crops and all that. They won't get more than a few days' "use" out of the cover crop when put into the next run section, before it is all extinct again. I wonder whether, unless your pens are going to be MUCH bigger, it'd be better to just give them full unlimited use of the whole area such as it is, and find other things to entertain/feed them with.
JMHO, good luck, have fun,
Pat