Since there would be no point to entering the refit screen to assign weapons to the Oasis, there's no limitation there. I think my biggest limitation is going to be "how much time am I willing to devote to the art."
I'm probably down for making something perhaps 1.5x - 2x as long as the Gila. We'll see. It's not going to be some kind of supermassive ridiculous ship, just real big. Since the ship itself will be larger than most capital ships, but will have no weapon systems, it's justifiable for it to have room for a massive number of people.
I'm thinking of setting very high limits on max crew, max cargo and max fuel. Only a skeleton crew would be required to fly it, say ~100, but the max crew limit will be ~20,000. Or in other words, enough crew that you could man several fleets, if they all suddenly vacated