The short answer is that the DISboards have a rule against advising ways to break Disney rules.
The longer answer...I am sure some people did. I did not even try. We could try this year...she is just turning 4 but is still VERY tiny, in 2T clothing now, but I feel very good knowing that I resisted the temptation and bought her a ticket.Last year, My dd was turning 3 on the trip. She was questioned by gate cast members more than once. And she was in a stroller, and was only in size 12-18 month clothes last summer -- she was TINY. Oh,and we had a copy of her birth certificate just in case. I wouldn't want to be made to purchase a ticket, and then seek reimbursement after the trip once I submitted proof.