My apologies for replying just now.
My wrist is 7 inches and not so round.
I can’t tell you about the lug to lug of the 43mm.
But for the 5002 it is 5.8~5.9’’. I have one and this is how it sits on my wrist.
I believe the 43 would work on your wrist. I say that after trying the 48mm Top Gunn on my wrist. 48 is too big for me but 46 works and so 43. See how the top gun 48mm is on my wrist and see how the 46mm of my 5002 works.
I hope this helps!
5002 at 46mm

Top Gun at 48mm

And comparison

Tibo