Me again. Tongue weight is completely dependent on the layout of your trailer. Being a rear kitchen will reduce your tongue weight. The general rule is about 12% of the trailer weight will be on the tongue.
This is a great site for Ecoboost trucks, but I suggest you go to RV dot net and visit the tow vehicle forum.
I'm interested in this as well. I have an enclosed trailer being built that can handle 10k. I expect somewhere around 800 to 1000lbs of tongue weight fully loaded. I already have a weight distribution hitch....In a few weeks I'll let you know how it goes.
I also have a tongue weight scale....so ill be able to dial in the tongue weight. The truck will be maxed safety wise at 850lbs of tongue weight....being that's all the payload I have. But I suspect 100 to 200lbs over will be just fine.
I have not towed 7500, but I have towed 7000 with the 3.31 rear end up a 5 % grade. The truck performed very well, it dropped down to 4th most of the time and dragged the trailer up the hill at 60MPH. As far as tongue weight goes, my trailer comes in at 13.75%, and I use the Hensley Arrow for weight distribution and sway control. The key for tongue weight is a great distribution hitch, and verify the trailer you are considering is not extremely heavy on the front. Another thing to consider, my trailer has a 90 gallon water tank just in front of the trailer axels, when this is full of water it adds ~800LBS to the trailer and adds significant weight to the tongue given its location.
My trailer is about 7800 loaded. It is a rear kitchen model so I put almost all of our stuff near the front to get the tongue weight up to 12%. If the tongue weight gets to light the trailer tends to wander a little as my control works better with more tongue weight.
As far as pulling it I have the 3.55 and I do not have any issues engine wise.