Here you go, the BG is ripped. Here's what the archive includes if you're interested:
-One .map16 file as the BG does consume a Map16 page and a half.
-Palette is easy to edit and the BG uses palette 3. A .palmask file is included.
-BG uses all BG1, BG2, BG3 and some FG2 tiles. There's room for FG.
-Included sample level with BG,
-Evil the Cat is animated. This is the part that did annoy me. Thank god for GENS.