Hi Andy,
All seems to be progressing well. I know a lot of folk are following this thread with great interest, so would just like to 'throw into the ring' another source of screws, bolts and washers that I have been using for almost 20 years in the building of my lifeboats - EKP Supplies, Nr. Barnstaple in North Devon, who make a lot of quality products for the steam model builders. Like you, I use a lot of Knupfer products, mainly their stainless steel very small sized bolts, nuts and washers. They certainly help to 'detail' a model. However, EKP will do the larger numbers and also in brass, which can either be plated - using one of the nickel adhesion processes [which I know 1709 has done to great effect recently] or else spraying [likewise with 17-09]. This works out a lot cheaper, especially when one has an engine access hatch to detail with either 110 or 220 bolts!! Also, if they are going to be covered in anti-slip paint [like on the Trent], then brass is good enough. They also made me to order, many years ago now, 1,000 brass 14BA bolts with a 12BA thread [this did not strip the thread in the tapped hole so easily] and these have been used on my Trent and some other areas of other lifeboats. However, made to order they did cost well over £200! - just don't mention those to my wife, and yes, I did not charge this item to the 'house keeping' account. Going back to your approach, I would always use the Knupfer stainless for safety snap-lines fixtures, pulpit and aerial fixings [etc.,.], they do give a great appearance and are less likely to rust.
[added with Andy's 'thumbs up OK']
Canterbury Coxswain