The truck will easily and safely tow 8k. I towed about 10k with my 2012 F150HD and a 7k enclosed trailer with my 2012 F150 Ecoboost 2wd work truck that had 3.15 rear gears. It didn't do it as well as my personal F150 HD with 3.73's truck, but it did do better than the 2011 F150 5.0L with 3.55 gears work truck I had before that. Both of the work truck only had the basic tow package.
If the tow rating of your truck is 11k, then that means you have the max trailer tow package and have a slightly different suspension than the regular F150. This gives you more GVWR and GAWR than the standard F150, and therefore more payload if that is a concern. You are probably between 1.7-2k payload if this is the case. Using the standard 12% tongue weight, an 8k trailer's tongue weight is around 960 lbs which will leave you plenty of rating left over for a small family.