Thanks for the reply re Giant Loop possibilities. I had forgotten that in order to really have waterproofness one would have to buy the specially shaped dry bags to go inside the saddlebags. The saddlebag itself is only described on their website as "water resistant". I think they could stand to make that much more obvious on the site instead of throwing around stuff about "trucker's tarps" and "mil-spec" (especially w/o calling out the spec itself). One thing about the dry bags is that they would serve to organize the load a bit, it could still be a hassle finding something to take out if you stop along the way.
Loved the report! Looking forward to your next one!