I see the Cantilever-cross brake headset hanger.. so this may not apply here and now,

To general readers .May I suggest a QBP locking spacer .. its like a seat binder band for the fork ,
so pinch bolt keeps it there .

Having an Integrated headset , doing the same spacer shuffling ,
the fork would fall out, headset and all .

Now , with the first spacer above the headset, being that , the fork stays in the bike ..

of course to re adjust the preload on the headset, all the pinch bolts around the steerer need be loose ..

heres what they look like : http://problemsolversbike.com/products/locking_headset_spacers