Please get out the owners manual, and determine your max tow rating and GCVWR, which will depend on your drivetrain, and whether you have the factory tow package. If you do not have the factory tow package, you likely have limited axle gearing, and 3700 lbs will be over your 3500 lbs rating. If that is the case, and you are towing with only yourself, and nobody/nothing else in the truck, you might be OK at 200 lbs over your limit. But if you will also have passenger and cargo in the Explorer, you will not be happy.
If you have the factory towing package, then you probably are good for at least 5000 lbs max tow rating, which will allow for 3700 lbs of loaded trailer and 1300 lbs of passengers and cargo in the truck. In that case, you simply need to figure out what you need to do, ralated to maintenance and degradation on a 15 year old truck.
