Taking two children camping is no small task. Even an adult alone requires a bunch of equipment. The car is usually stuffed so tight that my girls can't see each other and the passenger seat is filled.
That situation changed when I began using a Sherpak Go! 15 Roof Bag on my Assateague Island Trip of 2016. I packed the roof bag on the ground to see how things would fit but then I took everything out, hefted the bag up to the roof, and repacked it on top of the car.
At first I threaded one strap through the front car door opening and the back strap through the back door opening but the straps buzzed terribly and gave me such a headache I had to pull over. This was, unfortunately, right before I had to drive over the dreaded Chesapeake Bay Bridge. For my next trip I threaded both roof straps through the back door opening and the buzzing was more tolerable.
The roof bag isn't easy to use. At 5'4" I have to climb on top of the car every time to zip it shut and secure the straps. The buckles for both compression straps have broken but I won't really be in trouble unless one of the buckles for the main straps break (the straps that hold the bag to the roof). The Sherpa roof bag works and it does give more space in my passenger compartment but it's not easy for me to use.
For Assateague Island in March 2016 I also had another untested item to try out. I brought a Kelty Cosmic Down 20 Women's Sleeping Bag from REI. The first night of our trip the temps were about 25 at night and I had to used another lightweight down sleeping bag as a liner before I was warm enough to sleep. Maybe if I had worn expedition weight long underwear with two pairs of wool socks I might have been warm enough with the Kelty Cosmic Down sleeping bag alone but I was freezing. My Kelty Cosmic Down is ideal about about 50 degrees.