Like Hanno, I don't think the trailer is Canadian.
The Canadian frame has the C-channel has the open side facing inward (opposite to this frame). I can't access the Photobucket photos to see larger images (MLU prefers the photos be saved to MLU so that when photo hosting sites close or restrict access the photos aren't lost) but the hub doesn't look like the Canadian 15 cwt trailer (which has a body closer to the shape of yours but very different bracing pattern).
Photos of a Canadian 15 cwt trailer can be found at
http://www.mapleleafup.net/forums/sh...=trailer+saved
Photos of a Canadian 20 cwt trailer can be found at
http://www.mapleleafup.net/forums/sh...ad.php?t=29948
There was also a metal bodied 20cwt Canadian trailer that had a similar shape to the composite body shown, photos at
http://www.mapleleafup.net/forums/sh...hlight=trailer