I use 2 x 10 meter (30+ feet cables) in my REW testing setup. The soundcard calibration should remove any effects from the cables.
I sometimes use binoculars or a small telescope to see the computer screen while using my wireless mouse on my lap at the listening position. Not so much a laptop mouse as a lap dancing mouse.
Eccentric but useful when a system is widely spaced. You could even put the scope on a tripod. (as I have also done) Or use a computer friendly flat screen TV as your computer monitor. (I don't have TV-out on my computer)
The wireless mouse allows me to use REW's "Frequency follows cursor" while simultaneously adjusting the test level on the stereo preamp on the rack. This avoids overexcursion on my IB at high SPLs and VLFs. (100dB(C) @ ~10Hz etc)
I have one 9.5" step to negotiate on the journey from the rack to the computer. No blood has been spilt.... yet.