On theme baby girl name ideas

Hello all, my wife and I are expecting our second child and have been considering names for her. Recently, while playing with our 2 year old, I asked him, "What should we name the baby in Momma's belly?" To which he confidently and enthusiastically replied, "Blue Truck!" (take a guess at one of his favorite books...) After a good laugh we moved on, but as I have been trying to think of names, I keep coming back to Blue Truck.

To be clear, I have absolutely no intention of naming my unborn daughter Blue Truck. However, there is a part of me that is drawn to the idea of giving her a name inspired by her big brother, and the color blue. I am struggling to come up with ideas that could fit the bill, so, what are your thoughts?

Some potentially helpful information:

We generally like unique names that are actual names; no Tragedeighs.

We generally like old names that went out of style 75 years ago.

Little girl, due at the end of May, so a May baby with a small chance of June.

Middle name will almost certainly be Leigh (pronounced Lee).

Last name is a single syllable.