Discussing tow vehicles is like discussing TS vs FS outboards. Opinions differ and it can get heated. I will give you my honest opinion. But others will differ.
I had a 21SE before the 23SE. For the near shore ocean fishing I do, the 23SE rides better, particularly into a head sea. I can feel a big difference over the 21, which is also a very nice boat. The 23SE with F225 is fast at 49 MPH WOT. I tend to run it faster in a chop because it will run faster without pounding.
I tow with a 2005 1500 Suburban 5.3 L with a 3:42 rear end ratio. The boat, motor and trailer weigh 5700 # with a full tank of fuel but nothing else. I weighed it when new. I suspect it is running close to 6000 # loaded with gear. I think my Sub is rated to tow 7600 pounds. I do not have blistering speed from a standing start but it will do fine in traffic. Once rolling on the highway, the motor loafs along at 65-70. I usually try to maintain 65 but sometimes it rolls up to 70. If I were going to go any larger, I would need the 2500 or 3/4 ton model and 6.0 L engine. I do not intend to go bigger. The 23 is just right for what I ask it to do.
I do not know much about Fords but think you would be better with the Expedition. A buddy of mine bought my old 21 and does tow it with a V-8 Explorer. My 21 weighed about 4800 #. The last time I rode with him I heard some noise that sounded like trans or rear end. I did not say anything but I think it is a lot of boat for the Explorer. We travel together with both of our boats in tow. I notice the short wheelbase Explorer dips up and down much more that my Suburban. It is particularly noticeable at night with the head lights on.
If you are going to stay with the Esplorer and are going to tow long distances like I do, I would buy the 21 SE and put it on an aluminum trialer to save weight. I wish I had purchased an aluminum trailer for my 23. I still might. Also get disc brakes on all four wheels. Moving that much weight is one thing but stopping it is just as important.