The tag is a bit weird. I think it's some weird lighthouse in the BG and even that looks awkward. Still, here's the BG and layer 3 of Udderly Abducted. Had to do some layer 3 placement and did just that. You can:
-view the sample level to see how both the BG and layer 3 are set up.
-change the palette of the BG and it's quite easy to edit and uses palette 3.
-notice the BG uses 248 8x8 tiles, only using BG1 and BG2.
-see it uses 111 Map16 tiles, or almost a half of Map16.
-see that the BG can only be 256x256 and the layer 3 be 512x256. You can extend that if you please.
-observe a big layer 3 tile consumption. The layer 3 uses 330 8x8 tiles, also making this a big layer 3 tile devourer.
-see I enabled transparency to mimic the original.
-set the recommended BG and layer 3 scrolling to none.
-notice that both layer 2 and layer 3 have their own files required to insert.