In some of the Scum Epic discussions, the Sorosuub 3000 has been mentioned, and I've commented that although longer than the Ghost, it's much slimmer and [ignoring the engine pods] fits within the GR75 outline...so how about that as a candidate [and size example] for what you're proposing ???

[EDIT: the above is based upon Mel's model, which I'm assuming is correctly sized]

You wouldn't have a ship; you'd have a play mat that acted like a ship.

That's SWX58.