We leased a 2018 Explorer Sport with the 3.5 EB and only towing experience was a double axle U haul cargo trailer that was probably 3k lbs when loaded up. Power was awesome, I could tow that trailer at 70 mph all day long up and down hills....except for the 7 mpg and 18 gal tank that had us stopping for fuel every 2 hours. Could almost set your watch by the fuel stops. We put about 20k miles on the Explorer before the lease was up but zero problems.
This motor has been out for several years and don't hear many if any issues with the longevity on the internals etc. Gotta run premium gas though. I think for a 7K trailer it really comes down to how far and how often you tow, I don't think there's any question it will get the job done reliably.