I picked through the (incomplete) code base for the PT 2.0 software (which I will be uploading to a git repo soon) and option 1 is easily the best choice and the attribution file can be autogenerated once all the old PT data is uploaded into the system (or as much of it as can be since it relies on the header standardization. Additionally, the attribution requirements are already built into the system and will appear on every part page official or unofficial.
As for the current PT, adding an attribution statement to the texture pages should be easy.
As for the current PT, adding an attribution statement to the texture pages should be easy.