I can't speak to the Arctic Fox but the F350, properly setup, is a very capable vehicle. Our 2013 F350 4wd has been in some pretty rough places with the Igloo on board. The Igloo is around 3,400 pounds wet and fully loaded with gear for travel. In Alaska we did some pretty rough off road stuff but no rock crawling or crazy off camber stuff. Your 990 will weigh more than my Northstar. Get some really good tires, add at least stableloads and either sumo springs or similar and then try it out to see how it performs. Your center of gravity is probably higher than mine too, so that may limit your off camber travels. But logging roads, fire roads and the like shouldn't be much of an issue.
