>>11953130
Now I'm trying to get a feel for how large maps could realistically be.

If collision tile coordinates used 8 bits per component, you'd end up with a 256 x 256 x 256 grid for the whole map to exist in. This gives plenty of space to work with. You could allocate a whole WRAM bank just for collision data. If 4x4 metatiles are used, you could fit a single 256 x 256 collision layer in there (filling the entire x/y coordinate space, but leaving no room for other layers). In a more realistic scenario, there'd be no issue.

The background tilemap would take up the most memory of all. Using 2x2 metatiles, you could store a 256 x 256 tilemap across 4 WRAM banks. This should be plenty big enough, and still leaves a few WRAM banks free for other stuff.