Well, the best milage I've had was 7.9 towing a Honda CRV 4 down. Worst is 5+ but lots of stop and go in that mix. My 2016 35US weighs at 19,900 pounds while the CRV is around 3500.
Your Alante probably weighs less but that will offset with the added weight of the Explorer. If you get better than 8mpg you will be doing good. Double check your explorer weight, you are getting close to the 5000 pound hitch rating.
Nick, Sharon and Fin the wonder dog.