My husband and I have had almost every type of towable there is over the years. We now have an Aliner Ranger 15 with cassette potty, and a Cool Cat heat pump for a/c and heat (has a thermostat, just like at home) - we love it. It's a pop up, but it doesn't have canvas (not a fan; been there, done that, lasted only 3 trips). The walls our our Aliner set up in one minute. This is a good option if you spend a lot of time outside. It can sleep three, if you use the four person dinette as a bed. We get 16-18 mpg, towing with my 2010 Nissan Pathfinder. If you don't want to use the dinette, your son is almost old enough to enjoy a tent outside.
We also have a very small TT, but we will probably sell it within the next year or two.