You shouldn't need any c2p routine with gfx-card. I don't remember now what you should select in rtg-master prefs, but try to not select any c2p if it's possible

What screenmode you have selected? The best mode I've got to work with Napalm is 640x512x8bit on Voodoo3. Lower 8 bit resolutions work too.
Anyway Napalm works great on Voodoo3 here... it just flies with higher resolutions too.. and from different planet when compared to zorro2/aga systems