Look at the 3/4 ton truck.  Either Chevy or Ford (or Dodge, I guess LOL)
As others have said, price difference is negligible for the gas engines.  I tow a lot (my TT being the least of them), and I can safely say that a 3/4 ton will be will be better in every way except unloaded fuel mileage.  The ecoBoost can do it, but you're pushing the limits.  Pushing the limits too many times ALWAYS equals failure (everything, not just automobiles).  A larger truck will pull better, handle better, be more stabile, last longer, etc.  You can also throw all the payload calcs and concerns in the garbage.  Last thing I want to do right before a trip is be worried about the payload or tow rating, and whether or not I need to evaluate my weight.  I would also be concerned about the safety of an aluminum cab truck, and all other light-weight trucks.  At some point, you have to be worried about that trailer behind you weighing twice as much (or more) than the TV.  When a trailer of any kind that significantly outweighs the TV loses control, there's nothing stopping it from imposing its will on the TV.  Longer trucks, heavier trucks, trucks with better suspension, trucks with more tire surface in contact with the road...these vehicles handle such a situation better than shorter, lighter duty trucks.  Just my 2 cents...let the bashing begin LOL
But if you're dead set on the ecoBoost and you don't pull the TT around all that much, then get it and have fun.