o/p - I dumped my dunlop runflat, for continental dsw as well. Dunlop RF, were burning out at 15k intervals. At $2400 a set. On my third season with the DSW, and still plenty of tread. As you have no spare, you will most likely also have no jack or tools. For additional fun, I now carry a scissor jack, wrench, air compressor, tire goo and tire plugs.
Here is a thought for you. On your summer trip. A run flat tire will get you an extra 50 miles. How is that going to help in your 42oo mile journey? You're still stuck. Run flat, or traditional tyre.