My advice would be to go out and find the trailer that fits your family first. Keep in mind that it's fun for kids to bring a friend along - especially teens. Slides are nice on rainy days. It's not uncommon for people to buy a tow vehicle (TV) and then find a trailer that's too big for their TV. It's also common for people to move up to a larger size trailer once they get into RVing. In other words, it's not the worst idea to buy more tow vehicle than you need.
When you are shopping for a trailer it's good to know the abbreviations. The dry weight or Unloaded Vehicle Weight (UVW) is easy to find on a trailer and useless. The trailer will always weigh more than this. Salesmen tend to push this number. The Gross Vehicle Weight Rating (GVWR), which is the maximum loaded weight of the trailer is the one you'll want to find and go by when shopping for a TV.
When shopping for a TV the longer the wheelbase the better. Read up on how to estimate your payload so you don't overload the specs of the vehicle. This next part is opinion: your trailer shouldn't weigh more than 80% of what the tow vehicle can tow. Use the GVWR for this.
Good luck with your shopping!
PS - salesmen lie