The closest place would be the Suggestions forum in the Message Centre.
But you should know that the rules team is well aware of all the ships the Combine *hasn't* got, and most have reasons for not being implemented.
With your suggestions, one of the primary problems would be that all are Imperial ships. For the sake of balance, there would need to be a number of new Rebel ships as well - otherwise the Empire would receive a bunch of new ships and the RA would be screwed. (: However, I don't think there are any plans to introduce new Imperial/Rebel specific ships at this time, with the exception of the Interdictor.
Rules Team is not accepting new ship proposals. We have a list of ships we will add as "rare ships", some CP ships, and 1 or 2 more with the ship update. Anything else goes into R&D. Believe me I know how many ship and vehicles are in the star wars universe, my specialy is in that area.
"Somewhere, there's a bullet with your name on it. The trick is to die of age before it finds you"