What to do if it rains?

Since completing my Dart, it has never been driven in the rain. While not perfectly clean, the underside of the car is still "pretty clean." We are going out on our first multi-day trip this weekend for Carlisle, and it looks like there is at least a decent possibility that we may get some thunderstorms one or two days. For those of you who drive your cars, particularly with show cars, and don't have a trailer to tuck them away in when it rains, what do you do with your car on a trip like this? Do you bring along anything specific in terms of car cleaning products for a trip like this? I also don't currently have a good car cover because my Dart stays in the garage all the time, so it just gets a regular dusting. I don't mind the rain, but I hate to get my Dart filthy on this trip. Would appreciate any thoughts or advice.