Well I guess doing it one panel at a time may work ... but I think it would be a big hassle, I've never been a fan of leaf blowers...
ONR isn't like acid or anything but I treat it as such, you can never be too careful, right? I haven't had any issues with water in cracks and crevices because there simply isn't enough water to get trapped in there. I'm sure everyone has a different technique with ONR and some probably use more water than others as well. Maybe someone can do an experiment on a beater with ONR and let it dry on the paint (with dirty ONR solution) to see what happens?