Fortunately the graphics are not compressed, so you can edit them directly with a tool like TileLayerPro or YYCHR.net. Do the following:
* Save the OBJ palette when you have the pilot sprite on-screen (use the Palette viewer in VBA)
* Open a graphics editor and load the .pal file you saved
* The pilot graphics (back of head) seem to start at 0x112A48 in the ROM - scroll down or jump down to it
* Make your edits once you find it
Hope that helps! Good luck with your project.