So, I tried a couple methods. The way I calculate my character zCoordinate is like this:
z = (position.y * .001f)
So, that works with my characters. They appear above/below each other depending on where they are at on the screen.
So, with that working , I went with your first suggestion, using this formula to alter the position of the Z coordinate based on the position of each tile, and then covered my map with tiles on the layer I want to perform this logic.
(y * (x1 - x0) + x) * 0.001f)
So, this produces weird results. Most tiles my characters are visible over. However, as I'm moving up and down, there is a group of 4 tiles, every 10 tiles or so, that my characters will disappear behind.
So, I tried setting calculating the z Coordinate of the tiles based on how the y Coordinate is calculated, kinda like I do with my characters:
(tileSize.y * y) * .001f)
This works perfectly, on the bottom chunk of my tilemap only. On "chunk 0 1"- "chunk 0 5", it works great, but once I get to "chunk 1 0" and above, my characters completely disappear under the tiles.