What's the best way to set a destination for a retreating enemy?

I have an enemy that wants to keep it's distance from the player so whenever they get too close, the enemy picks a position a set distance behind them, checks if there's a viable path and sets it as a new destination for the NavAgent.

Code (CSharp):

1. public void Retreat()
2.     {
3.         //If the skeleton is already far enough from the player when this is called (from taking a hit), ignore it
4.         float DistanceBetweenTarget = Vector3.Distance(transform.position, PlayerTarget.position);
5.         if(DistanceBetweenTarget > MaxDistance)
6.         {
7.             return;
8.         }
9.  
10.         //Debug.Log("I gotta get outta here!");
11.         Vector3 RetreatDirection = transform.forward * -1 * RetreatDistance;
12.         Vector3 FirstDestination = transform.position + RetreatDirection;
13.  
14.         SetPath(FirstDestination);
15.     }
16.  
17. private void SetPath(Vector3 Destination)
18.     {
19.         //Check if the destination is on the navmesh
20.         NavMeshHit Hit;
21.         bool NavMeshFound = NavMesh.SamplePosition(Destination, out Hit, 1.0f, NavMesh.AllAreas);
22.  
23.         if (NavMeshFound == true)
24.         {
25.             //Check if there's a viable path
26.             NavMeshPath Path = new NavMeshPath();
27.             NavAgent.CalculatePath(Hit.position, Path);
28.             if (Path.status != NavMeshPathStatus.PathInvalid)
29.             {
30.                 NavAgent.SetDestination(Hit.position);
31.                 Moving = true;
32.             }
33.         }
34.     }

This is of course pretty basic and there are plenty of situations where it gives up on running away because its back is facing a wall or it's on an elevated platform and isn't considering jumping down. I'm not sure how to handle this because I usually know the destination in advance, is there any good videos on pathfinding that cover this situation?.

 

Hey!!
I wanted the same results soo I added an empty gameObject behind the enemy and added a mesh to it and baked a navmesh. So now whenever the enemy is too close then it sets destination to that gameobject