Use #6 wire and you won't have a problem. I wired my home garage subpanel from the main panel (35 ft. run) to supply 50A for my tools using 6-3 w/g. Passed inspection, no problem. When I moved the Progressive EMC unit in my 3670, I found the wiring was #6, so I just used some of the left over cable I had to reposition it. You might get away with #8, but #6 will give you a safety margin.