Damn, this is tier 2 slave looks amazing! I would place her on third place among others judging by her appearance. Too bad it's paywalled (I can't become patron right now). I don't care much about customization option, because I prefer their personality and backstory without me deciding it and other tier bonuses, I just want that girl.
She is also in the game banner, such a trap!
So, I was thinking about this space dilemma and I remember back in the day Grim was saying about game engine and that is hard to make it. It was before annex was added IRC. But now it still a problem? Can't we just build another annex, or build additional floors in the first one? As I said, don't know much about codding, for me, it looks like, you could program additional page switch when you go to slave selection menu, and switch between them like: page 1, page 2 ...