I'm still doing some refining of the code, but for the brave amongst you, attached is V4.00 (beta) of the Regional mesonet-map.* scripts.
Please note that 2 images have been added to MESO-images (layers.png and layers-2x.png), otherwise the image set is unchanged from the V3.x series.
This will support a Mapbox API key to enable two additional maps, but does not require an API key to use the 5 built-in maps in the script.
Let me know any issues found. I hope to release (with docs) the V4.00 version later this week.