Okay, so you have already decided to do 10 more and get out as a LT/LCDR and retire. Okay, you have no aspirations to stay in til 30 and try and be a CO...currently.
That being said, who cares what the detailer wants. If you want SSBN, do SSBN if the billet is available. Why? Well, you obviously are familiar with S8G and hence would have one less thing to be worried about. You have the 8G maneuvering time as an EO/Th/SRO/EWS?(I guess) so as a JO you would possibly be a hot running JO, qualify EOOW quickly, impress your chain, and be more able to focus on sub driving.
Then do your shore and then screen for DH and head to an SSN or SSGN or NR-1 or whatever. I may not have all the answers but, it seems logical to do what is the easiest transition.
I mean by the time you reach your 2nd shore tour, would it really matter what you did when/where as long as you qualify for command and have good Fitreps? Seems to me pretty nonsensical to care which platform you do if you don't plan on staying on for XO quals.
Of course I was just a lowly blueshirt, I could be wrong.