Personally, I didn't expect us to be close enough to the coast for salt air to be a problem. My Slingshot is kept in a carport, but is still exposed to the outside air year round. I'll have to keep any eye on the rust as I can't afford to replace my Slingshot. I try to avoid riding when I know it's going to rain, but I worry about eventual frame damage.
In seven years we have never worried about riding in the rain, and we have never shied away from allowing it to get wet with no obvious excessive rusting, so far. There is another downside however where it is a real pain in the @#$ to clean back up.
Bill