I used to be an electrician for 25yrs and have always read those charts as the max current(37A) you could draw for 1000' run with acceptible voltage drop. If you were only drawing 20amps your drop would be less. If there was no load you would have full voltage at 1000'.
You must however figure an inrush current of about 300% whenever a compressor motor starts up, if this takes you over your 37A you will have a problem.(some motor take less) This is one case where a 220V motor is an advantage as it takes 1/2 the amps of a 110V unit.
