A Star Destroyer map doesn't have to contain every single cubic foot of the ship! The major sections would be fine; the bridge, one of the engine rooms, turbolaser fire control, barracks, mess, detention area, etc. I've seen huge maps before that would easily compliment a Star Destroyer.
I'm really surprised no one's made the bridge at least! It's an iconic set; especially when you consider people have made Death Star and Kamino maps!
Fortunately (for my machinima fan film) a modder has made a terrific ISD bridge map that I'll be using.