What about using a sprite anyway? You could have a sprite animation with several hundred dummy frames, then iterating through the number of maximum frames you want to import / the number of maximum "slots" a.k.a. sprite frames.
Depending on your content structure, you could handle different animations per sprite style, eg. wall tile, floor, etc.
On object creation, you determine the animation name (wall, floor, etc.) + sprite skin, which is the given frame number.
Loading huge tilesets this way would also result in a bloated V-Ram, but I think that the bargain between tiled bg and sprite is not in your favor