I have an old large Thule Evolution. It's 3' wide and 92" long. I used to use it often on my old Sequoia for skiing and scout camping trips. The problem with the Pilot is that the cross bars are not adjustable to be further apart and forward for it. I had when I was using old long straight ski's (197-205cm). everyone now is on shorter shaped skis so could use a shorter box but this is paid for long ago. I put it on for my son and his friends to go skiing in March. On the farthest forward setting it was still about 10" too long on the back and I couldn't open the tailgate more than 1/2 way or it might crack something on Pilot or box. Mine has metal bars reinforcing the front but there was a good 2ft plus hanging with no support over the sunroof. Most boxes aren't that high or wide so you need to decide what you will be using it for. Luggage might not fit in it. Weight is also a concern (vehicle center of gravity) and of course noise.
For scouts on Sequoia we used it for tents and duffel bags/packs. It gave us room for more people to sit or put bigger stuff like stoves/coolers in truck.
Thule Terrapin goes into trailer hitch that swings away, they also have one Transporter Combi. I don't like the look but it is an option and maybe better for some. ETrailer has other walled cargo baskets also.
