I just cleaned out my Weber - no salt in the bowl, but everywhere else, yup.
I think it's just as likely that the heating and contraction of your own fuel tanks would cause that. They'll heat up faster and higher outside than the large tanks in the ERC trailer, and cool down quicker and cooler than a large body of liquid would. That combination, in conjunction with the likelihood of higher winds at night, kicking up salt, while the tank is cooling and drawing a vacuum would make a plausible scenario for a carbureted vehicle.
But I will say that that seems like a lot of salt for a motorcycle carb.