Just some random meandering thoughts on observation points.
I'm currently reading the most recent couple books in the series, so I haven't gotten into the ironclads yet, though there was some mention of the possibility of iron being used as framing in a recent passage, so it's possible that some of my comments are dated
I have no fear of spoilers though, so I read through the first few pages of this thread.
As drawn, I would be concerned. That rear observation post would be almost impossible to man to any good effect. A single forward observation post would probably be the only permanent observation post, I'd think.
However, there is an alternate solution to this, I'd say. This might or might not be something that's been used before. You have several smokestacks, why not build an observation post onto every smokestack? Your observers would be able to use a varying number of observation posts, depending on the speed of travel and the wind and atmospheric conditions. As a general rule, The worse the weather, the more observers you could have.
I do not know the exhaust temperature of this class of steam boiler at the point it leaves the smokestack. If it's above 140F then observation posts built onto the structure of the stacks might be problematic, as you would have severe issues with keeping people functional unless you built the observation posts well above the tops of the smokestacks. The ladders would also need to be insulated from the smokestack at the base, almost certainly, or they wouldn't be climbable without heat protective hand and footgear.
I've personally done manual labor in temperatures of 140+F, next to a steel mill's reheat furnace, with near zero humidity, and it was awful. It'll hurt you badly if you aren't very careful. I can't even imagine how bad it would have been in high humidity. Even if the lookouts aren't doing anything strenuous, you would have to shift them in and out regularly if the exhaust temperature of a stack created an environment at the observation platform of 120F+
If the Smokestacks are turned at the top, towards the back of the ship, it would probably be a lot more possible to put an observation post on them without endangering the lookouts. I know I've seen top-turned smokestacks, but I can't remember if I've ever seen them on images of real steam era warships.
**EDIT I found references to "Macks" a combination of Mast and Smokestack, which were used by a few warships. Here's the best image I found on short notice. The funnel is back-turned as well.
http://upload.wikimedia.org/wikipedia/c ... rawing.jpgThese apparently were not very kind to electronics mounted on the Macks. Safehold navies don't have that to worry about for the time being.