As I plan to move soon, I'm thinking of hitching a 4x8 U-Haul trailer to my 2001 2WD Eddie Bauer Expedition and loading the trailer with maybe 400 pounds of stuff max. (Trailer is 850 pounds empty weight, so call it 1200 lbs loaded.) What sort of reduction in highway MPG can I expect expect? Also, how much of a strain would even this minimal trailer put on a 20-year-old transmission?