Custom trail fixed length and custom form

Hello guys!

Here is my problem.
I need to achieve effect like on the pic attached. The white trail is trail like with builtin trail renderer, but it has custom form, and fixed length all the time. How can i achieve that? I guess I need to write custom trail renderer, which will spawn meshes with the desired form. Anyone can help with that?

For the fixed length:
private void Update()
{
trailRenderer.time = Mathf.Abs(1f / rb.velocity.magnitude);
}
This basically just checks the current speed the rigidbody has and then turns the time around to make if fit the current velocity magnitude. @Rocknglory