So remember everyone: MAKE SURE THE TANK CAN ACTUALLY FIT THROUGH THE DOOR!
I feel your pain, but I couldn't help but chuckle because this is precisely the kind of thing I would do ..... and have done! Built a spiffing plywood tank into my basement years ago (assembled the tank in the room), only to discover upon moving that the tank wouldn't fit out through the door. Was possible to disassemble, but still.