Would you recommend a hose or a big bucket? Sorry can't resist, damping a panel and dampening are two different things. But as he said you need to first figure out what is rattling and then stop it from doing so. He is correct that a screw here or some foam or sound damping material in a few spots can make all the difference.Find what's rattling and dampen it.
I find that leaving the windows down overnight lately seems to produce great results. If possible roll the windows up after the fact and avoid using the defrost to prolong dampness.Would you recommend a hose or a big bucket? Sorry can't resist