I would go for 2, 4 of an mix of those 2. 5 is allowed by the guidelines if nothing else is possible (for example,
http://shipbucket.com/images.php?dir=Re ... Kievit.png) but that seems not to be the case here.
option to explore (the abovementioned mix) would be to have the 'side facing' windows get the full, 3 pixel bars, and the 'front facing' windows having the single black bar. the problem is, with rounded shapes as these, were to put the switch between those 2 without getting an quite hard 'bend' in the looks. (one bar of option 5 to avoid this would not be weird to me, but I am not the one to decide this of course)
note that the other superstructure windows at the front suffer from the same problem, btw.
your effort to imrpove an already great drawing is commendable, btw. keep up the good work!