I'm going to disagree with you there. I tried calling DAN for advice about scopalomine and diving. Their answer was "we can't help you with that as it has not been studied. You should call your doctor"
Given the litigation risks in the USA, nobody will provide any medical advice on drugs if clinical trials have not been run.
One of the key drugs used for primary immune deficiency (intravenous immunoglobulin) is used extensively off label and it works in the majority of cases, but nobody will promote these off-label uses.