assigning several positions and call array of raycasts

I have a object that follows my cursor that i can build and place with a mouseclick. I can place it on a grid but i need to make restrictions where i cannot build. The places where i cant build are next to other objects and have edges of the object that are outside of the grid.

 Ray ray = Camera.main.ScreenPointToRay(mousePos);
 
 submarineZone[0].transform.position = new Vector3(mousePos.x, mousePos.y, mousePos.z);

I will call the ray on mousePos (which just is = with Input.mouseposition). I want to make an array of Raycasthits that will also be called but around the cursor. For my object that is 1x1 i need to have 8 raycasthits called that will check if other objects or restricted areas are next to it.

For example i need to change the Raycast Vector of submarineZone to this:

 new Vector3(mousePos.x, mousePos.y+1, mousePos.z) 

and i will check a block right on top of the cursor with the raycast.

However i could just edit all these raycast positions individually but that would eat up too much code and be un-efficient. How can i go about assigning the elements of the raycast arrays that will surround the cursor.

When i have bigger objects i will just divide each part of the object into 1x1 and have them call array raycasts around them so that wont be a problem.

So that i want to know is: Should i just hard-code each positions of the raycasts or can i do this in a way that doesnt need me to paste the same code over and over?

Thanks