I was in the same boat. You have to be able to show and document (i.e. in detail) your comparitive managerial experience. I claimed a Part 91 "Chief Pilot" position (has no meaning to FAA) supervising other pilots working for an aircraft dealer, but it didn't fly. My Part 135 SIC time was not considered either. Had to wait til I was able to document 3 yrs culmultive PIC Part 135 time (in the last 6 yrs I think, also) until I could serve as the Chief Pilot and upgrade our Single PIC Pt 135 Operator to a Basic Pt 135 Operator. Somewhere in the 8400 handbook tells you what you need and how to submit it. Had to do the letter over agian because it was not in the correct format. We had an pilot earlier who started our 135, who had no135 time, got approved as Chief pilot, but he was able to document a wealth of military and civilian command time and managerial test pilot time.