Indeed, basing the rank solely on number of posts would be unpractical. I mean, what with Premium/Elite Member status?
I guess it would have to be done in such manner, that higher member status would have to immediately translate into promotion (for example: Premium = commissioned officer, Elite = admiral - or something like that) and not getting Premium/Elite promotion would block getting rank over certain level - otherwise, for example APDAF (with over 1000 posts) would have much higher rank than BB1987 with less than 500 posts.
Btw. - what about FD Masters? Assuming that they make mostly land/air drawings, should they get Army/Air Force ranks (or at least Marine Corps ranks)?
Generally I don't think those navy-styled ranks are really needed.
That said, I would like to thank Emperor_Andreas for bringing forward interesting issue and his effort put into presenting it.