My M3W is only in use from May to early October in the South East of France and spends the rest of the time in secure, covered storage. For the most part, those are dry months (very dry this year, my cherry trees have died), with just the occasional thunderstorm. The car actually got wetter under the Morgan "all weather cover" than it does without. I am now happy just to lean on the tonneau cover and dry it off with a chamois leather if there is overnight rain. It saves me washing it, which officially is not permitted at the moment anyway. For years I have used synthetic chamois leathers made by a French company called Neoclean. They are better than a natural chamois and miles better than any other maker's synthetic, including expensive ones from the likes of Autoglym. They come in a near airtight container and can be put into it damp with no risk of them going mouldy. I really cannot understand why in the 25+ years I have used them, the rest of the world has not caught up, but it seems to me that they haven't.
Wilson
