It just occurred to me that the executable from Flight1 may only detect FSX. If that is the case and that executable doesn't work, here are the textures that are used. I'm not even sure if these textures are the same in P3D or not, but it sounds like they are. Be sure to read the ReadMe file. I'd backup your originals first to the desktop. Even though there are .bak files in here.
Back again - same problem - now wanting refund!
in Prepar3D
Posted
What I have found works great to fool the installer. rename any .exe file to FSX.exe and place it into your p3d folder.