With respect to crew problems for the subs, what about make the life of the subber very good, like going out to sea 1 month per year just, and the rest of the time with simulators and going out maybe 2 or 3 days, for example once or twice a month for 4 days plus the big out of one entire month, in peace time, so the subber has lot of spare time, good money, most of time at home, you can have many subbers able to rotate using the subs, so less time per crew at the sub...also for the crew number of smaller subs, for ex the s80 has 32 crew, so one collins crew gives for 2 s80´s, and if smaller than s80 maybe still less. But for that you need good simulators, for ex the s80´s tactical sim: type in youtube "SIMULADOR TÁCTICO DE ADIESTRAMIENTO PARA LOS SUBMARINOS DE LA SERIE S-80A" .
Also you can type in youtube "LHD JUAN CARLOS I segundas pruebas de mar" for the second sea trials of the jci with interesting movements.