[duskwuff]

You'd end up with a cable that only worked for "slow charging" (5V / 500 mA), and even then only in one direction (because the cable could only pretend to be Rp+Ra or Ra+Rd for one side). It's easier to do the right thing.

[hedora]

I wonder how much a crappy voltage regulator costs vs. 3-9ft of wire. Maybe you could step the voltage down at the device end?