Maverick,
Without seeing the actual model, it's hard to say why you model is so big. But looking at the pictures I'd guess that you're not using components as much as you could. It looks like there are mostly repetitive features in the model. You should bundle these up into a small number of Components and repeat them.
The second thing is your use of textures. It appears that these textures are highly detailed in the pictures. For optomized SU models textures like these should probably be less than 10 KB. I'd use your photo editor to fix you textures for good tiling, i.e. set a big horizontal overlap and maybe tinker with the image to improve tiling. then import them into SU once and let them tile in the model.
The third idea (and again I can't tell from the pictures) are all the framing/support structures built as elements in SU? A way to cut down on the size of the model; is to set these up in your photo editor as a picture with a transparent background. Then save as a PNG file. In SU just make a face where the structure would be and import the PNG image.
good luck,
Tom