Thank you Richard. True and very sensible observations. Couple of thoughts.
The Frame File is an obvious first stop although John Alexander's later edition - The Expanded Frame File is the one to go for. It has full details of Joe Beeby's metal frame. And John has an amusing way of warning of the vanishing wing nut!
I use wing nuts but not to undo and remove. That's the road to insanity. But they are useful when you simply slacken them, allowing the pieces secured to fold.
Now here's a little tip. Don't use a bolt so short that it is only just long enough or slightly over slackening will result in a lost wing nut. Instead use a slightly longer bolt. However you can still lose these when they work themselves loose which they always do. And you might just catch yourself or a puppet on the protruding bit of bolt. So cover this with one of those so called bolt or screw covers.
These are soft plastic, often black (I've seen other colours) and come in a range of widths and lengths but look like a tiny bearskin hat soldiers wear. B&Q used to have them until they got rid of their small hardware section. The last I bought came from a kite shop and are used for covering the ends of plastic kite struts. They're just a push fit.
You need as tight a fit as you can get but if there remains some movement use a drop of weak PVA glue to hold in place. Then should you need to remove the wing nut it will cut through the trace of glue.
Beware of using steel bolts and washers and wing nuts with aluminium. The two metals react together resulting in corrosion due to a cathodic reaction. I'm no expert but imagine you would get away with it if you used fibre or plastic washers between the bolt head and the wing nut and the ali strip.
The biggest question mark in my mind is the strength of ali outside and the wind factor. We all know how strongly the wind can blow but it's the gusts of wind which tests frames. Town centres can be very difficult - wind bounces off the buildings, specially in squares and can come at you from different directions at once, twisting the frame.
I'm beginning to wonder whether most of those post war 'aluminium' frames (either made in the then running down aircraft factories or from surplus wartime materials) were actually Duralumin and not aluminium at all.
Just out of interest those of you who work events where old fairground rides feature will have noticed Helter-Skelters or Lighthouse Slips as they are known. Tall, look like lighthouses and stand out on fairgrounds. Look hard and mentally lay the thing on its side and what have you got?
The fuselage of an aeroplane and that's what they were, more or less. Made at the end of the war in the aircraft factories from aircraft metal and using the fuselage jigs. War Surplus was the genuine thing in those days and exceedingly cheap. The post war fairs and circuses were equipped out of war surplus and all sorts still turn up.