For the gen 5 Explorers, it seems clear that:
a. w/o class 3 tow package, you can only tow 2000 lbs, period.
b. with class 3 tow package, you can tow up to 5000 lbs if you use a WDH
What is unclear, is what can you tow with the class 3 tow package, but w/o a WDH. Since there is some increased cooling, and they call it "class 3", I do not believe it would still be limited to 2000 lbs. But they clearly say you can't get 5000 lbs w/o WDH. Therefore, it seems logical to limit things to 3500 lbs, weight-carrying, with the class 3 package.
And I think this fits the bill. The Explorer is no longer a truck. 4th gen didn't need WDH until 5000 lbs. But the new crossover is more softly sprung (and that's OK!). But more than 3500 lbs means likely 400+ lbs of tongue weight. That's probably about 560 lbs added to the rear axle, and 160 lbs removed from the front axle. It's at this point that vehicle dynamics get affected. You want to use a WDH to get that weight back on the front wheels.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller