I would be careful about throwing underweight balls....by nature the arm is going to move faster and stress levels can go up. I would probably throw a regulation ball at reduced intensity, but, thats just me.
I would want to do the same sort of recovery as from a sore arm. Active recovery. Cut way back on the throwing, get the blood flowing, isometric holds, electro stim, shoulder tube ect.
Sometimes guys here rest and they thing "do nothing"....recovery should be active in my opinion unless it is in relation to a specific injury.