ElizabethN (OP), your TT is about the same weight as ours (6,500 empty / 640 empty tongue) & we also have the EQ4 1200. The dealer setup the WDH for what he expected our tongue weight would be when loaded. Therefore on the way home from the dealership it felt bouncy - like it was porpoising up & down too much for my liking - and this was behind our Ram 2500 CC w/stiff rear springs that can handle a payload capacity of 3,000 vs. your Ecoboost's 1,760...
However, once we loaded our gear we're at 8,000+ w/loaded tongue of 1,200 and the ride feels totally stable now. (Tongue weight increased by 50%; now 15% of our TT weight...) Once we had some pretty high winds so I added about 300 lbs. of water to our FW tank (up front) making our tongue weight closer to 17% and stabilizing our setup even further by lowering the TT's center-of-gravity. However, I do not recommend towing with a full FW tank on a regular basis...
The problem with the F150 EB is the softer rear-end / payload limitation of 1,760 means you have to dial-in the WDH just right to keep 15% on the tongue & not go over on your rear axle rating. Therefore a lot of F150 EB folks tend to add airbags to stiffen the rear axle. Since you have already upgraded to E tires, your next step is to adjust the EQ4 WDH by following the manual/YouTube videos step-by-step. If that does not work, your last option is to add some affordable air bags. It seems most folks are happy with the results.
2011 RAM 2500 ST Crew Cab 5.7 Hemi
2011 Primetime 3150BHD Touring Edition
Days camped in 2016-36
Days camped in 2015-37
; Days camped in 2014-31