I would say that it depends on the plane. For example. The Beech or Grumman_Goose, or any sea plane that also has landing wheels, can back off beaches with ease, just deploy the landing gear and shift 9 to reverse.
Sadly any float without wheels that deploy you have to be very very careful as They forgot the paddle you use in real life, so you have to use the Y key. It kinda looks like a paddle. I did find if your plane has 2 engines you can use the real life method of using one engine to push and the other to pull so you actually turn enough to get out of the position you found your self in,