One of the reasons why we bought the Catalina 400 is the large aft cabin, with a double bed with access from both sides. Since we do coastal sailing, it is very easy to use. I like an aft cockpit, as opposed to a center cockpit, so my boat was best suited to my needs. The bed does not have a lot of head room, but is comfortable for us.
One modification that I have heard about is to install a divider in the bed which allows the use of lee cloths to make a true sea bed(s). I can think of several ways that this can be done. I'm still thinking about how I would do it on my boat. I would have this done if I planned to go offshore.
As to the thread drift about production boats vs. custom boats ("... even a well build production boat is not without risk..."). All boats on the ocean are risky. All small boats (less than 60 ft) even more so. This topic is so beat to death. The appropriateness of a craft for a specific voyage is much too complex to be addressed by such general statements. Posting about specific models, or specific modifications, or specific preparations is really helpful.
Back to the original post. Yes, there are a lot of larger aft cabin yachts that can make excellent cruisers. Some are ready to go. Some may not fit your needs, but some may be modified to do so.