For the data argument's sake, I browsed internet and found unreal engine game that allows the user to preview all interiors items. You can also save your progress into file and continue other time.
This save file containing around 400 furniture objects is somewhere below 150kb in size. If we would pack more data like exterior, garden, etc, let's round it up to 200kb.

If everyone had large with 200kb "save file"
that is 200kb * 30 plots * 2 subdivision * 30 wards = 360 MB.
so the one world's housing database has 360mb.

Let's pretend everyone on the server has also apartment or fc room with the size of L, being it another 360 MB.
So total 720mb per world.

I don't want to be rude but I'm not very into the storage argument. Last time a 720mb was considered threat to storage was in year 1994.