I have the same basic Expy as you. My trailer has a 25' box and is about 30' overall (actually a bit longer with the rear platform pulled out). We had our rig weighed back in April and loaded for travel was 6,200 lbs.
Our Expedition has the power to get us where we want, but I have to be willing to shift down and let the RPMs do the job (e.g. 6-8% grade climbing up to 8,000' elevation I was in 2nd doing 40 MPH).
I'm light on tongue weight and I'm using an Andersen WD hitch. We currently have issues with sway above 60 MPH. I need to see if changing tongue weight is my issue, or if I need a different WD hitch system.
