He mentions 20 in as an adequate distance for smaller speakers in his paper, but I was concerned about the dB scale not indicating sensitivity accurately. The speaker is probably somewhat less than 80dB at 1m and that is what I'm measuring at 1m, unless I'm totally off about this.
Sensitivity will not be correct. But for designing crossovers it doesn't matter as long as the source and mic position do not change.
Prior to taking my full speaker response measurement at 1m, I run a 1KHz sine signal and adjust my amplifier output to read 2.83Vrms at the speaker terminals. I also take my tweeter and woofer in cabinet measurements with the port plugged and a 22uf cap on the tweeter. For near field on the woofer, this is too loud, of course, I adjust the "input volume" on REW preferences from 1.00 to .5.