Ford can't keep Raptors on the lot as it is, even with dealer markups. I doubt very seriously if Ford is worried about the three guys who won't buy a Raptor because it doesn't come with an ecoboost.
Every single person on the F150 forum that has lifted their Eco and installed larger tires has reported a loss in mpg's (duh). Now let's use some logic... MOST Eco f150's are considerably lighter than Raptors and ALL F150's are 7 inches narrower. A larger front profile and more weight will absolutely have a negative impact on mpg's.
An Eco Raptor wont get 20mpg, or 18mpg - how do I know this? Because the Eco FX4 guys with a lift and 35's are getting between 15-17mpgs and they are 500-800lbs lighter with a smaller front profile.
I'm not sure why anyone would be asking for a Raptor with very similar mpg's and less power.