I'm far from the weight police, but...
I think you have too much trailer and not enough tow vehicle.
That 215WSK has a "dry" weight of 4355 lbs....that's the dry weight which doesn't include propane, awning, microwave, etc. (even the "mandatory" options aren't included-just the box and the frame). By the time you get all the "extras" added on, you'll probably be looking at 4600-4800 lbs. Add another 150 lbs. for a WD hitch and you are already looking at close to 5000 lbs and that's before adding equipment (dishes, pots/pans, drain hoses, water hoses, etc), food and clothing along with grills, lawn chairs, etc. and I'm going to give a WAG of 5200 to 5500 lbs. The trailer has a max load of 5960 lbs, so, 5200 to 5500 lbs. would be a good guess if you watched what you put in it. Over weight already.
Add to that the '05 Sport Trac has a 6 cylinder engine, underpowered for that weight, and yours is going on 8-9 years old (age takes a toll on equipment, no matter how well maintained) and I think you will find the Sport Trac will be less than what is needed. I have a friend and he tows a similar weight with a Jeep Commander, Hemi powered and it is "borderline". I towed, in the day, a 210WBS with a Hemi Jeep Commander and it was adequate, but, even the Hemi had to work in the mountains. Your 6 has 2/3 the horsepower and half the torque to haul about the same weight on an older chassis.
Another thing that people don't think about is the frontal area of the trailer. The Sport Trac, while it's best "tow rating" is 5300 lbs, that 5300 lbs. is aimed at a utility trailer or a boat that has minimal "frontal area". The only frontal area rating for the Sport Trac that I could find was for a 2010 and it was 60 sq. feet (that's a 2010 with the V8 engine). Your trailer is 8' wide by 10' 6" high. That's 84 sq. feet...too much for the V8 and way too much for the V6. Those are Ford's specs, not guess work.
Those are the numbers. Can you hook it up and tow it off the lot? You can (if you have a 7 pin wiring harness - I found references to a 4 pin and that isn't going to work with your trailer). Will it be safe? No. Is it going to cause accelerated wear and tear and possible catastrophic failure of your Sport Trac? A 9 year old V6 not rated for the weight or frontal area; yes. Would I do it, and bear in mind, my current rig is right on the edge,? No. IMHO, if you like the trailer (you bought it, so, I'm assuming you do), then you'll need to get a suitable tow vehicle to haul it with. You are in the full size SUV / full size pickup truck arena with that trailer. You don't need my 2500 CTD, but, you do need a healthy V8 or small diesel and a bit more vehicle weight.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)