"31ft Trailsport" is the trailer and I'm guessing it probably weighs at least 7500lbs.
Very few vehicles exist with at least 3 rows of seating and can comfortably tow anywhere near 7500lbs.
You have to consider the fact that you are carrying what are essentially SIX fully-grown adults and their stuff in the vehicle, and that is going to KILL your payload capacity. Even if you average 120lbs a person, it's still 720lbs just in people. So whatever you choose as your vehicle needs to be able to deal with 1000lbs+ of people and stuff, plus at least another 1100lbs of tongue weight, plus have the power to move it at highway speeds under normal driving conditions.