Editing Trainer Hill floor maps

[GriffinRichards]

This is sort of a "thinking aloud" suggestion but I wanted to record the basic idea in case I or someone else is later interested enough to implement it in some form.

Trainer Hill in Emerald is a battle facility with 4 floors that the player battles trainers in. A 16x16 area of each floor changes depending on the challenge. The map data for each floor is stored separately as an array of secondary metatile id numbers and a bit array for collision (elevation for all spaces is 3). Example here.

If a user wants to edit these maps with Porymap they must convert this data to a layout, insert it into a blank 16x16 map with the correct tilesets, and convert it back when they're done editing. Here's the first floor of the default challenge after doing that:

Converting between the two formats makes editing these maps difficult. Perhaps Porymap could support this by allowing layouts to be edited by themselves (#182) and loading/saving the Trainer Hill data with the proper conversions. I haven't put much thought into what form that might take in the interface (separate editor like the region map? same 'layout editing' view but with additional limits imposed like the lack of border?).

An alternative general solution to the difficulty of editing/viewing these maps would be to allow exporting metatileset images. A user could then edit a .bin file with the metatile data by loading it with the exported image in Tilemap Studio (though they'd still have to edit the collision data separately).
EDIT: Re: the above, I have done this but it requires forking Tilemap Studio, as it doesn't support tile sizes that aren't 8x8 (and with map data and a metatileset you'd be editing in 16x16 tiles)

EDIT: The equivalent Trainer Tower in FRLG is much simpler, and has ready-made layouts in the normal format. All that's required to edit those is layout-only editing support (or the current workaround of adding a dummy map to the layouts)