Upload & Sell: On
When I look at this, the thing that concerns me is not so much direct water droplets touching electronics, but the indirect moisture that could occur in the next few months due to temperature changes, fine mist that you can't perceive but exists, and condensation due to the heat of the unit being outdoors in anything except warm sunshine.
I started to look at pelican cases (http://www.pelican.com/cases_detail.php?Case=1460 comes to mind), where you could create a custom molded interior for the flash (not foam), but instead a heat resistant gel. You could modify the case so that you can plug the power cord in, with an o-ring to seal it off on one end, then have the case contain a light stand fitment to mount to the stand itself, then have the reflector on one end either sticking out, or better, self contained with a clear cover, all contained and sealed in the box minus ventilation where applicable. You could create a water resistant chamber so that moisture can't enter in, but air can escape.
Just a thought, because you'd then be able to transport the lights pretty quickly and easily with handles on the cases already...