Here's the bulk of our automotive fleet:

20180610_140943 by Numbchux, on Flickr
This was taken about a year ago, there was an SVX parts car that was not pictured, and since then I've acquired 2 '01 Outbacks, one for parts, and the other repairable.
We have a 2.5 year old daughter, who struggles sleeping in strange places. We love to camp, but over the last year, trying to get a good night's sleep with her in a tent has been a struggle to say the least. Our theory is that a trailer like this would allow a familiar space that's a little better isolated from sound/temperature changes would help her. Not to mention simplify camp setup and teardown. We also enjoy getting off the beaten path, so something designed to be small, light, and with good ground clearance is a must. We have a couple friends that bought campers like this and love them, but the price tag for pre-built ones is insane!!
Last fall, we drove out to the tip of the Keweenaw peninsula in Michigan (my daughter stayed with my parents, though).

20180902_082907 by Numbchux, on Flickr
Which is about 15 miles of Forest road. A bit rough, but our stock Outback had no trouble:

FB_IMG_15360773225444218 by Numbchux, on Flickr
I'll be building the trailer with the idea that it's tires can be used as spares on my 4Runner, as it'll be pulling most of the time. And a camper of some sort would be very nice for base camping to do some wilder offroading with it.

IMG_52134495177976 by Numbchux, on Flickr
Every fall, some friends (I made it one year, it's been tough with the kid) go out to Colorado and Moab to go Mountain Biking. But the plan is to make it a family camping trip more than a hardcore biking trip for next year. So the goal is to finish this thing in time to have it tested and usable (I'm not going to say "finished") by September 2020.