David
You seem to have talked yourself into a "I cannot win" condition.
Do the set that you know and enjoy it - show the judges that you are enjoying it, have fun with your audience and let them have fun as well - hype them up.
As its magic/comedy I would look at a "singers always win" type joke but done with you singing VERY badly -Perhaps a faux opera style.
Or tell them your are going to sing an Australian classic from Kevin Wilson about a young girl who is friendly and you believe her father may own an establishment that produces alcoholic beverages. (I am sure you know which song I am refering too)
I would also get a friend who can do a not too bright Aussie Drawl to re-record the bandana backing (use the same timing).
If you do not win be gracious in defeat.
David
As it is getting close to Christmas - Kevins Wilson's other classic:
A young boys lament to father Christmas as to non receipt of his preffered mode of transport.
I cannot think of another Kevin song at the moment, but perhaps describe three of Kevin's songs in the above manner to the Judges and let then choose - tell them it's the only songs that you know - Let them squirm for a few seconds then say "I can do a little magic as well" Then go for it.
I am brainstorming this as I write.
I would start with the three choices of Kevin songs, then "I can do a bit of magic" bit. If you have props already on stage have them covered to look non descript at the start.
HTH
Paula