Im surprised to read that the captivated nuts in your body are fine thread,im fairly sure that the shield bolts are course thread. I dont have my parts book to hand ,but you mention youve looked at yours in the 'seat' section. The problem with that ,is im sure the shield isnt in that section.
Im sure it comes in the section for the fuel tank
. The four bolts you mention ,im sure you,ll find it also lists nuts for those bolts. They,ll be for fixing the two sprung steel rear seat clips on the inner panals I think? Also got to question the mounting screws in the picture you posted. My parts book(45 issue) certainly states hex heads 1/2" means no provision for a wood strip.Is the strip an early v late thing? Certainly no wood on my 45 gpws.