I'm not sure if the atmospheric pressure also has an effect on the map itself.
Other way around: Planet Size --> Gravity --> plus a bunch of other factors --> Atmospheric Pressure (afaik). Larger planets should tend towards more atmosphere; and also towards more geological activity, thus further tending towards more atmosphere.
I can see approximately what you are looking for in terms of game play. But I would say that its actually a more difficult request to fill than you realize. Planet generation depends on a specific fantasy Planetology, right? So while technically any map can be drawn, only certain types are possible to generate. Just like in the real universe.
So the question becomes: What is the complete story: Geological, Biological, and Socio-Political, of this Moonscape? What kind of real life planet is it analogous to, as far as Science can tell for now?
For example: how did it fit in to the Galactic Empire? Was it, like, some sort of Space Truck Stop, maybe? If there are no resources *at all* on it, why are there people on it at all. And why are people fighting over it now? If there are no resource tiles, what are those factions fighting over exactly, anyways. Should we prepare for an ultra-low population scenario?
I guess you just want to try playing on a particular map type, simple as, so maybe making up a story to answer all these questions seems beside the point. Fair enough.
But that story is necessary to different parts of the game in several different ways, Without some kind of answer to the questions about the Planet's history, and the parameters they give to the Planetology system, it seems like it might be pretty hard to actually make the game work at all, except in some kind of skirmish mode, maybe.
-----
...maybe there is a moon map, *attached to* a planet map... like a 'hyper-map'... ha... I always like those kinds of boards... anyways, I know I havent helped you find what you are looking for. Sorry and good luck.
edit: You could just halve the scale size of the map hexes on an otherwise normally generated Planetoid. Instead of each hex representing 200km, it could represent 100km. I mean, a mod should be able to do that. That would give you exactly what you want, maybe.