Thanks for the Trip Report! Your trip is like a mirror image of my trip starting with my drive this Friday out of Denver to Bullfrog. Will have 11 people total, 5 adults 6 kiddos. Gonna be a blast, really looking forward to it. I too am hoping for a little monsoon clouds to start up.
Sorry but I too am about to hijack the thread about the F150. I sold my beast of a 2007 Dodge 3500 Cummins 6.7L in January and replaced it with a new body 2015 F150 Super Crew, 3.5L Eco with Maxtow, 6.5 bed. I've put a little 2.5" level kit on it and one size larger tires as well as rear spring helpers. I wanted most of the capability of the Dodge but with much more comfort and so far so good. But your post and the replies after it have me worried! I too will be towing about a 5500# boat, but also about 1000# worth of gear, coolers, kids, etc.
Before the Dodge I had a 2005 Duramax Crew and it was an overheater. HATED that truck going to Powell. Nearly melted it on those rolling hills into Bullfrog Those 2004-2005 LLY Duramaxes were known to overheat. So when I got the Cummins it was a relief to have a truck I could pull as fast and as hard as I wanted to in 105 degree heat and 11,000 foot mountain passes. I don't want a repeat performance of the Duramax, I guess I'll have to watch those engine and tranny temps closely, especially on those climbs out of Denver, over the Divide and Vail Pass. Another thing I'm worried about is the engine braking or lack thereof. My Cummins had the Exhaust brake which is a lifesaver. My trailer has surge brakes, but I usually lock them out because they will get so hot coming down the mountain passes that it will liquefy the grease and sling it all out of the bearings. That 3.5L while it has good pull has like ZERO engine braking capability. I guess I'll just have to slow down my drive a bit from what I'm used to on the Dodge Cummins.
I suppose I should do a trip report here in a couple of weeks and include my experience with the F150 3.5 Ecoboost.....