I would ghost the BO, saves lots of weight, and as you said, he contributes nothing of importance.
Planesman elite, classed on time and vetted. Yes, either that or a +15 pot with +11 res.
Sonarman: 2 options
(1) elite pot classed on time with lots of vets. Does not contribute lots of restore and repair, but will give you a tiny bit of an edge with sight range underwater. Look up the ability values needed for the respective sight increases.
(2) +15 pot with +11 res (or even +14 pot with +12 res) left support until lvl 50/60.
2nd (rear) torpman ghosted
1st torpman: +12 torp is sufficient if he has +11 res. As the torp cap is so low (850k), I'd even go +11 torp with +12 res, leave him national sailor and only class him armament sailor around lvl 50 and then torp man.
I wonder what is better for engies: 10/10/12 classed on time or 11/11/11 left support until lvl 50 (or even higher) and then classed 2nd engy... Vet the heck out of them and you have a very strong boat.