My understanding is that 20' is the standard. Mine was built a bit longer at 22'. If I were to build another house I would pay the extra for at least 24'.

I can walk around the back of my 01 and 08 SuperCrew with 5.5 box. I could open the tail gate on my 01 with the garage door closed. I have not tried it with the 08 Screw yet.

The 09 Screw with 6.5 box is 20' 3" so it will fit in my garage, but I'm not going to be able to stand behind it and open the tail gate. Not even if I suck in my gut.