(Other than being standard in SuperDuty), I could see the engine lineup something like this:
XL standard 3.7 V6? (if this engine will be put in the F150 at all), optional 5.0 V8
STX standard 5.0 V8
XLT standard 5.0 V8, optional 6.2 and EB
FX standard 5.0, optional 6.2
Lariat standard 5.0, optional 6.2, EB
King Ranch standard 6.2
Harley Davidson 6.2
Platinum 6.2 optional EB.

I honestly have no idea, but this is how I would do it. I might even go as far as saying that the 6.2 V8 might go with the Max Towing Package - which ever trim level you buy.