I guess I should add that we are in Georgia, very near Savannah. Please, if you are aware of anyone who could help, please ping them...or ping your lists if you feel this is worthy of a ping.
God bless!
Do you have freecycle in your area? It is an online group where you can ask for or give stuff away.
I see most answers saying to talk to the Scout master and search the troop closet. That has already been done and they had (1) one uniform in his size. They are going to try to find more by putting out a plea in the next newsletter...though that will not help for this trip.
I will try to answer the other suggestions individually