Good advice here! We have a F150 ECo and just upgraded from an 16' box to a 22'. Based on recommendations on this forum we went with a Coachmen Apex and love it, although our model is more for two people and would not work for you.
My one bit of advice, like others have said, do not believe the salesmen. Believe the numbers. I started out every time telling the sales folks we wanted to stay below 4500lbs dry. That was personal preference for comfort towing not the trucks limit. With only one exception every place we went was telling us " you know you can tow 9500lbs with that Eco ". My point is some folks will sell you anything to get you off the lot and money in their pockets. Beware!
You should find easily find something to fit your needs and trucks capability.
Good luck!