unity – How to highlight edge of movement range

I am working on a small tactical game like X-com.

I now have a working-ish version and would like to treat myself to some aesthetic upgrades!

I have been thinking hard about the following but I can’t seem to figure out how to “nicely” highlight the edge of my movement range.

I would be looking for something like this:

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As you can see the mesh range is highlighted with smooth corners.

At the moment the best I have managed is to simply instantiate a “tile” prefab at the correct locations:

enter image description here

This leads to all kind of funky artefacts like the fact that the range gets hidden behind any objects. In the following image the character can actually move onto the wooden porch but the tiles are instantiated below it (see red circled area):

enter image description here

I suspect a shader approach where the range is projected onto the camera might be a better approach… I could then add a shading to the bits of the range behind objects whilst still showing it. Problem is I have no idea how to go about it, and couldn’t find any tutorial online.

Help most welcome!