There is an easy fix for thatBad artwork supplied by customer.
Design whatever you want and put it up for direct retail sale on the interwebs. Don't need no stinkn' customer-provided art! Of course, every solution comes complete with its own set of problems ... like the joys of, more or less, screen printing on demand based upon what retail customers ordered that week. Lots of screens to clean for the number of units printed (and all water based, so can't be lazy and not clean them).