Depends on if you plan on calibrating any CRTs or just fixed pixel displays.
In addition to a nice long HDMI cable (I use a 10 meter, though the last 5 meters is only used maybe 2% of the time), I carry an HDMI coupler. It is a little passive thing with an HDMI female connection on each end. It allows me to just unplug the HDMI cable from their cable box or sat receiver and join my cable to it. Then I am assured my generator is taking the exact same signal path as their source, and I don’t have to reach behind the TV to plug in my HDMI cable.
I also carry a 5 meter USB repeater extension cable, handy for the C6 or i1D3, and a small roll of blue painter’s masking tape.
Also, an LED headlamp and small flashlight are necessities.
