Yea, with a 4,700 lb. tow rating I think you are going to find the pickings very slim with something that has a toilet/galley/shower. You might be able to get away with a pop-up style camper that has an open utility deck, but from what I've read those can be difficult to manage in temperature extremes and won't have the full feature set you're looking for.
One product I did come across in my hauler search was the following:
http://www.sporthaul.com/products/boss.php
I knew somebody who had one and towed it comfortable with their Honda Ridgeline. However, with a dry weight of 2,600 lbs and a GVWR of 7,000, you would be able to fully load it out with your setup.
You will also need to consider the payload and hitch limitation of the 2014 4Runner. Payload is about 1,500 lbs depending on trim, and may hitch weight is 500 lbs.
Additionally, keep in mind that your 4Runner, with the limited torque of that V6, is probably going to struggle to keep up to highway speeds and navigate inclines. It's not so much the weight, but the frontal surface area that really puts a hamper on towing and gets exponentially more difficult as you get over about 55mpg.
