While it's not huge, there is a model of the Rebel Transport in the old Hoth Rebel Base model kit. It's about 9 inches long and would need detail work but for just one or two shots, and background material at that, it might be doable. If you're re-creating the same shot exactly then you only need to build it up enough for what you're going to see, which appears to be starboard side nose area.

http://www.starshipmodeler.org/gallery8/jp_hoth.htm

That's just one example I found at Starship Modeler.