I too share a deep love for homeworld, and GW killing the BFG homeworld mod, a fusion of two amazing things, made me sell my 40k army
Don't call them mantas [
] but this idea actually has promise. I dig it. I'm not sure about having to deploy them from launch bays, as even if it were a fourth the size of a destroyer, its still too large for a bay I believe. But if there was still a limit based on parent ships that would work, you could say the limit per bay thing still applies as they hitch on to the outside of carrier ships, but I would just limit them, if they need a limit, to a certain amount per point size or capital ship number.
I quite like the idea.