Creating a plugin to extend TileMap node

Godot Version 4.2

I’m trying to create a plugin to add functionality (described below) to the TileMap node, and I’m having trouble finding where to start. I understand the basics for making a plugin, but do I need to parse through the 5000ish lines of code for the base TileMap class to find which members to overwrite? The plugin tutorials I’m able to find end at the very basic. Does it sound like it would be more straightforward to just write a new controller from scratch to handle tiles? I know this is a broad question, I’m happy to clarify anything.

The functionality I’m trying to add: I want to have more robust height functionality for 2d tilemaps, and the first obstacle I’m running into is how the tilemap places oversized tiles. It currently anchors to the middle of the tile (left side of example below), I want to be able to have it anchor to the bottom (right side of example below). Currently I’ve only been able to get it to work by adding a bunch of transparent dead space to the bottom of the hex, which far less than ideal.

Alternatively, if there’s a built in way to do this that I overlooked in my research, that’d be great too.

This seems like an issue that can be address by painting a Texture Origin onto the tiles. This way you can offset the texture in whatever direction you want for it to be aligned how you want it to be within the cell.