Little girl floats down river children’s book

I read this book when I was little and it’s driving me crazy that I can’t remember the name! I read it in the mid 1990s so could have been published in the 80s

•	it’s Short, not a picture book (felt ~20 pages).
•	Little girl or boy, likely orphan / on her own.
•	She gets in a small boat / raft and floats down a river. I thought it was the bayou but could be a random river 
•	She thinks she’s a pirate on an adventure.
•	I thought she Had a pet (maybe a frog and maybe in a box / jar / pocket).
•	Meets a boy along the way.
•	There’s a clear bad guy adult.
•	Dark-colored cover.

I know it’s NOT thursdays child or summer folk.