Is there a way to switch off sprite or general gfx rendering on a per-line basis? As I've seen for chained sprites setting the height to 0 would disable it. Would changing height a rasterline later show it again? And would palette writes cause no color noise during scanlines not displaying any sprite?
If that's the case, we could simply switch off the sprite rendering every other scanline and write the palette data instead. If not, there would still be some scanlines left between the different sprite blocks (e.g. in a non-vertically-interleaved pixel mapping). Higher res would lower pixel mapping requirements anyway.