My sister and brother in law tow a similar trailer with an EL with the Ecoboost. They also have three kids and a decent size dog. My guess is they're bumping at or a little over some of the ratings but it works okay for them. They did upgrade the tires and I guess that helped some. I'm not sure I'd want to go on a multi-state trip regularly with the setup but I doubt you'll have problems. If you want to be sure about the numbers the only sure way to tell is to run it over a scale.
FWIW, we have three kids and a crew cab pickup and it works great for our family on towing trips. The kids have to sit three in a row but it's a roomy seat. Nice thing about a pickup is they are a better value compared to full size SUVs and it opens up the option of going HD. I won't ever buy another half ton if that tells you anything about my personal opinion.