When I moved last spring, I ran through torrential rainfall and was fearful water got into the frame of my Rover. Fortunately, I haven't seen any damage. It sits on an Alpaca carrier with the crank to the top.
Is there any kind of bike cover you could use when the trike is on this rack. If I go to Michigan for Riderfest, I would definitely want one then. I'll probably see many storms in late July/early August.