Not that camper/RV envy is a new thing and most wrestle with it, you and/or she will probably always be checking out the neighbors and comparing. It's human nature, especially when something BIG is next to you. Who cares - you've got what you've got and it doesn't matter what others think about it. I recently got a tour of a 5th wheel designed to sleep two people with just about every foot of both sides being slide-outs. The media center up over the hitch area was awesome with leather couches and a large LCD that rises from the cabinet. Too bad they didn't have the washer/dryer installed yet - they were just trying it out. Great. Not why I go camping. To each their own.
My Explorers only had 3,500 pound bumpers but weren't Sport Tracs. If I added the tow package, then I could get to 5,300 pounds tow capacity but it involved more than just adding a receiver hitch. The transmission on the more recent of the two also choked pulling a similarly sized PUP (a Jayco 1007) and THEN I did research on the history of Explorer transmissions and found out it was a matter of when, not if, the transmission would die when towing anything.
BTW, your Sport Trac is 4,135 pounds curb weight. It has a gross weight of 5,660 pounds when loaded up with 1,525 pounds of people and cargo.
DavidP is right in that the rear of the Explorer is too soft. There are ways of fixing that. I went with air bags for the rear coils of my 4Runner and that has made a huge difference. Again, get the tongue down close to level. And shift more weight inside the PUP to in front of the axle to add more pressure on the tongue. Most people will always quote the 10% they've heard over and over. That can be just fine. I found that I need 15% to 20% of the weight of the PUP on the tongue for mine to tow well. I use a pair of same model bathroom scales to weigh my tongue, which comes in around 470 pounds. That's pretty much on the nose for the 3,100 pounds when loaded up. My scales go up to 290 each so I am comfortable enough with those measurements. So, how you load up can affect things as well.
