As others mentioned first check the weight and height. If everyone is on the heavy side there might be an issue of not being able to use the pull down..
Also I would not do it, less because of space.. On a short cruise all I need is a bed. If that means people crawling over me, that is ok.. for such a short trip. You will not be hanging out much in the room. Getting ready can be planned.
Where I have an issue is the bathroom situation. TMI, but I like to poop in private... this is where IMO a split bath is not good. When sharing a hotel room, I like to do my morning biz, and then shower to cover up the smell of what i just did. A split bath with a WC, it's obvious what one is doing so long in there. in a combined bath, I can do my thing, brush my teeth, get ready and shower etc.... . I can only imagine in a single WC room with 4 adults who are not intimate, how that can be not so pleasant.