Oops! Apologies Peter and Joe - lack of sleep must have affected my wing orientation!
I've had another look, but again, nothing conclusive. Some photos appear to show the three recognition lamps, whilst a couple seem to show a plain area, without lamps, but with what might be a small blister-type lamp, possibly a 'repeater' of the wing-tip nav lamp. The photo posted by Peter looks similar and, although this seems to have the outline of at least one more of the circular lamps, I'm not sure that darker patch is one of the three, looking more like the 'blister' mentioned.
Certainly all other P-51s and F-51s, on further viewing, have the three starboard recognition lamps, and as this was part of the design, I would think that CAC Mustangs probably had them too.
I'm fairly sure I've got a clear photo or two of CAC-built Mustangs, though I haven't a clue where they are - either in one of many books, or possibly a magazine article. But I also think some museum pics of Aussie P-51s have been posted here on the forum - if they can be found!