Two weeks into it, and my experiment hasn't worked perfectly. There are some water droplets in the light that I 'fixed' which is better than it was - and it has been raining often over these last few weeks.
I chose not to go the route of buying new lenses because a $5 tube of silicone is much cheaper and it was a worthwhile experiment for a weekend project. I think the whole thing only took me a few hours that would have otherwise been spent doing something less productive.
The water didn't and doesn't bother my wife at all, she just wants the van to work and not make noises.