Funny, people read a question, don't comprehend, and just throw out their favorite answers.
Your two best choices are going to be going with the F350, and raising the trailer.
Or, stick with another F250 and add bags like you had before.
Here are the 2015 specs. Does not give ground to bed rail dimensions. But it does show how one model compares to another. The "J" dimension for example, shows how an F250 compares to an F350 SRW or DRW.
2015 Superduty SpecificationsHere is 2014 if you want to compare model years.
2014 Superduty Specifications