It is easy to know if your 5 year old is too good for rec...if she is your kid then she is too good for rec. I don't know if there is 4U but there should be. How else can you get a girl ready for her 6U TB team is she doesn't play 4U rec? And we all know 6U is when things get serious.
Don't forget the Toddler League. They can just do their business in their diapers on the field!