Thanks for the input guys.
From what I've been reading, I'm somewhat optimistic that I might be able to average at least 15mpg on the highway if I keep a light foot. When I travel for work I just set the cruise control and sit back and listen to audiobooks. If I can manage at least 15mpg on the highway then it's pretty much a no-brainer, as I can buy a vehicle from a dealer that's essentially perfect for what I need. I don't care about mpg when I'm out "recreating".
The width I suppose might be a concern, but I would hope that the advantages of having a wider and more stable vehicle would outweigh any potential disadvantages. Sometimes deep ruts get cut in the snow on those roads, but I don't think it would stop me getting where I was going. Definitely don't care about any pinstriping, as my main concern is function. I truck bed lined my Audi and I'll probably end up Line-Xing whichever truck I end up with.
I really don't want to get into modifying a truck if I don't have to, especially if the end result is minimal overall gain in fuel economy.
The used 5.4 could be an option, but as everybody here knows, these things hold their value so well, I haven't seen a used 5.4 at an attractive enough price to make me want to go that route vs. buying new. Plus I'm looking for a truck with minimal options and those seem harder to come by.
Thanks again for the opinions, would love to hear what any others think.