I am looking to purchase a used Ford Expedition to be used lightly around town but mainly for towing a 4000 lb travel trailer. I have a few questions, but please let me know if there's anything else I should know before buying. What is a good year for the Ford Expedition in terms of reliability and towing? What's a good mileage target for a used Ford Expedition? Are they reliable past 175,000 miles? Do I need the heavy duty tow package for 4000 lbs provided I have a good weight distribution hitch installed? Thank you!