Vintage alleycat ideas, please

I'm turning over the idea of organising a vintage-only alleycat race for the springtime, here in Minneapolis. Thus far, this is what I've come up with:

• 1977 cut-off date. Nothing made after that.
  
• All frames must be steel (Easily checked with a magnet)
  
• Geared bicyles welcome, but limited to internally geared hubs, or derailleurs and 10 speeds. Not 12, not 14. 10 speeds.
  
• No index shifting, friction only.
  
• SS/fixed bikes must have cottered or one-piece cranks.
  
• Points awarded/time slashed for mechanical oddities. Anyone with a Positron derailleur gets a minute off their overall time, anyone using the Integer freewheeling crankset gets a minute off. Like that.
  
• No dual-pivot sidepull brakes. They bug me.
  
  
  

I'm having trouble coming up with ideas for checkpoint tasks. I don't want to make them annoying, but they should be challenging. Any and all ideas welcomed, though if it's fookin stoopid, it will of course be mocked.

Thanks,
Blight