What an amazing experience this will be, Jane! I'm not the best person to offer advice on travelling light, but do suggest taking a look at Angie's wardrobe capsule post on the blog. It may be a good way to identify your wardrobe needs on the road. I also wonder if at least one dressy outfit may be a good idea. I know so many of our European forum members have talked about the higher bar for casual in their neck of the woods, and wonder if some of your day trips into major cities couldn't benefit from a very small capsule to address that possibility. Obviously you'll have a hard labour capsule too (great idea, btw)!
All and all, best of luck preparing for this exciting adventure!