I dislike
Trudy, it's a nickname to me.
Gertrude is ok, but I think I prefer
Gertie as a nickname.
I like Tru best on its own. But it always sounds kind of silly as a first name. Try making combos: Tru
Marie, Tru
Isabella, Tru
Wilhelmina, Tru
Liana (you always think: Tru
Liana? as opposed to fake
Liana?) you know? It doesn't make the best first name but I love it, especially as a middle name. My favorite combo is
Adelaida nn
Ada True.
Oh yeah, I'd definitely spell it True. Tru just looks misspelled.
Some celebrity has a daughter named True Harlow and there are a few more with True as a middle name such as
William True.