"He who marches out of step hears another drum." ~ Ken Kesey
If you are doing frat shirts for a chapter of that Fraternity it seems to me you should be fine with any copyright issues being they are a functioning part of that organization. Would be different if it was some guy off the street. A licence would be geared more towards retail sales not event shirts to the best of my knowledge.
Hey Jon -Could you contract it out through a licensed printer in your area? Keep the customer, make money, avoid licensing issues (if that does actually avoid the issues).