I am going to echo the oil analysis. It is the absolute best way to make this sort of determination. The 3.0 Vulcan is a bit of a wheezer, but bless it's little spark plugs it is durable. I am usually in charge of my grandmother's '91 Aerostar, and I do one year oil changes on it using AmsOil 5W-30 and AmsOil filters. I did change the filters twice a year per AmsOil's recommendation prior to the release of their new EaO filters. She drives quite a few dirt roads and "goes to town" (50 miles round trip) once a week. The oil analysis has always come back acceptable -- not great, but acceptable. Even when, like now, I am almost two months over due to change it. At 120,000 miles, it still only uses a quart or two over the course of a year as it always has.
Go with AmsOil or Mobil 1 EP and pull a sample each time you come home at least for the first year, and I think you will be happy with the results. From the experience I have had with AmsOil's EaO filter, I would not be worried with it going one year whatsoever. I am not sure about filter change intervals with any other filter, as I have not played with extended oil changes with any filter beyond AmsOil's.
Good luck!