I realy like the design, but wow, your close to 20k already?
Here is a little advice. Please don't take this the wrong way, i'm jest trying to help out a new modder to BC. I think your coming from a different school of thought. If memory serves my, you came here from Scifi meshes, so i assume you learned modeling there. Most meshes there are awesome, but very high in detail and polys. You said that you current model is nearly 20k already, i'm thinking that maybe that you might be using for a lack of a better term, waste polys. If you check out Red dragons sovie you might get a better idea of how to build for BC.
http://bridgecommander.filefront.com/file/Soverign;55553I took a look at one of the best detailed sovies, the CG sovie, and its polys hit 13085, and it is very detailed.
I'm not trying to discourage you, i cant wait to see the finished project.