Question 2D Custom Tiled-Sprite Shaping

Hello, any help with my problem would be appreciated:

In my (2D) game I have need for a dynamically-made, shaped trigger area, with a tiled sprite filling its background. The shape of these triggers/colliders will not necessarily be box-like, they can be polygons of any kind.

I need to tile a sprite neatly within the trigger area, and then add a boarder to this area if possible.

I've photoshopped an example of what I'm aiming for:
https://imgur.com/F4LZl2Q


Much obliged.