How about differnt types of GB 1+2?
GB1+2 for tier 1+2 BB and CV + SS
GB1+2 for tier 3+4 BB and CV (+PBB) + SS
GB1+2 for tier 5+6 BB and CV (+PCV) + SS5
That had this idea, because BB1+2 are pretty useless vs. a bb 5 or 6.
The same for CVs.
So everyone could enjoy a "fair" game with equal chances.
But it makes no sense if the BBs and CVs in the tier 1+2 rooms use their lvl120 sailors, so there should be a lvl cap
for each kind of room, something like at lvl+5.