I'm trying to get a RSO type maze with an open starting area with 1 or 2 Mixed Ore patches.
So I've lowered the 'resource stretch factor' to force trains, while still using the Dead End resources.
Also using 'Maze Width=21' and 'Clear start chunks=9'

This will generate a path/wall on either side of the starting area, but it's hit/miss whether there is the starting mixed resources available.

If I lower the 'Clear start chunks' value, I usually get a large field of ore and a small chance of mixed ore.

What I'm aiming for:
Large open starting area.
1 or 2 Mixed Resource ore fields.
Several Chunks into the maze before finding Dead End ores.

Is it possible?

This is intended, but I'll look at adding a dropdown to control how clearing the start area affects resources.

Logic-wise, could it be possible that if the starting zone is configured to be larger than the map width, there will be 1/2 (configurable?) mixed ore patches in a corner?

Why in a corner?

If the player is setting the starting zone to cover the entire width of the map, I'd assume they want it for building, without an ore field in the middle.
That's my thought

Sure but the mixed resources are there just to get started, and won't last until late game. With a decent size maze the corners would be quite some distance to travel.

These sorts of settings already make the mod easier and more like vanilla. If you're going to drop the challenge of building within the maze, I think it's better if you at least build up to your ideal way of organising the base, not start with everything "just so".