Theoretically, this idea is a good one.
However, the everlasting problem in NavyField is that the time it takes to fill up a normal GB can range from a few seconds to several minutes. If GBs are limited by ship types, it would take even longer for these rooms to fill up. Furthermore, the division of ship level would lead to newer players who are getting their first BB1 for example, to be outplayed consistently by veteran players leveling their 2nd, 3rd, etc. line. In the normal GB setting, this is usually balanced out by the presence of higher tiered ships.
Just some things that came to mind when I first read your post. I would like to restate though, that I think your idea is pretty good. It's just that NF doesn't have a sufficient number of players to justify such a system.