Good advice, of course, but stryped actually misquoted Pedro, who wrote: "stand my poles plumb", (poles, not holes) ie, line the poles up and make them vertical.
AIUI, about a dozen different people have told stryped to put the poles 4' deep -- to handle wind load -- but he is still talking about 2' deep -- "easier to put in the poles". It may be that stryped is planning to lay each pole on the ground by its hole and then lean over, pick it up by hand, and put it in. Obviously he needs to be educated about a better way to handle the poles. For example, line up the back of your trailer with the hole; let about 3' of pole overhang; cinch the pole to the trailer edge like a hinge; swing the pole up, maybe using an A-frame on the trailer; uncinch the pole and let it drop straight down.