I've read several threads on oil but haven't found much info on what filter is considered the best to use. Is there a preference for which filter to use when running extended drain intervals?

If possible find M1-211 by Mobil 1 and it has synthetic fibers for better filtering then papaer filters, I am not sure but I think AMSOIL has a synthetic fiber filter. If not using a synthetic filter, then I would stick with OEM. Your extended oil change range will depend on what conditions you are driving under and oil used, but if it is basically just street/highway driving and a high quality synthetic oil designed for diesels then there is no real reason not to go the full 12,500 miles. I will be doing 10,000 mile oil changes just for ease of remembering when it's due.