Hey Frank,
Yeah, I have to say, when I heard Ken say you were doing your maiden flight for your new scratch-built 2-stager on a C6-0/C6-? combo, I audibly said to myself "You've gotta be kidding me?!? In this wind?! No way he's getting that one back!" But nevertheless, I applaud your bold attitude in pushing the limits, and in taking the loss in stride with a plan to immediately rebuild.
To answer your question on maintaining build records for the future, I do something similar. I actually keep the original balsa sheets from which the fins were cut out in a ziploc bag, in case I ever need to replace a lost fin...Hasn't happened yet, but I've got the patterns if I ever need them. I also keep meticulous build records for each rocket I build in a binder, along with the instructions, marked up to indicate how I deviated from the base design. This makes it easier to remember exactly what I did when the time comes to make repairs. I also keep my sims for each rocket in the binder and bring it with me when I fly. I'm up to my 3rd binder at this point...The plastic storage box I bring with me to launches is starting to get heavy.
On the subject of replacement fins, I once got a kit (NCR SA-14 Archer) which came with an extra fin. Wasn't sure if that was intentional or a packing error. But I just shaped and pre primed the fin like I normally do when I did the original build and set the extra aside with my fin templates in the event I ever needed to replace it. Here again, have never had to use it, but it's there. Maybe that's the reason I never needed it?...because I had it. Certainly if I ever do build a rocket without keeping the fin patterns, I will surely lose a fin and need to figure out how to make an acceptable replacement from scratch.