Never ever buy an off lease or rental vehicle! I know way to many people that beat their lease vehicles and never maintain them at all! Rental vehicles are very well maintained but again get beat on from day one until they are sold.
If you are going to buy used buy from the original owner not a dealership. Ford has closed their F-150 plants to change over to the new alum. truck and will be down for three months+. I would bet the leftover trucks will be picked over and the only thing you will find are trucks not set up for towing unless you look right now.
Don