I've suggested a similar idea a few times: Mog Furniture.

Initially, all furniture (placed or not) is moved from Mog Safe to Mog Furniture. (Afterwards, this is done manually.) MF only allows furniture items to be placed in it, contrasting Mog Storage. Placed furniture remains placed, so mog storage remains intact.
Size of MF depends on size of Mog Safe.

This allows for freedom to design your moghouse as you see fit, without it choking your mog safe. You want that collection of statues displayed? Now you can. You want a chocobo stable without dropping that lvl 99V2 emp weapon? Go ahead!