This week I have practically killed myself to bring you palette swapping.
No it's not as simple as it looks. To perform palette swapping quickly without using much RAM I rebuilt the Tiles file into custom forms. For your benefit I have included the tools I used to build them.
Download it here.
Rar file, 800 or so kB.
Notes: Sudtrap, I can't seem to reproduce your doors bug. If you can, try pressing D a few times until you see the doors values and take a screenshot for me to see.
Also: If you want to see the other palettes then just press 1 2 or 3 on the keyboard in game to switch between them. I've added breakables to Brin01.mcl as well to make getting across the room easier.