It sounds as if you're looking to maybe build a floating house? The big obstacle to overcome is going to be waste, how to both store and dispose of it. Even in a marina situation it often necessitates to need to move the boat to the pump-out station to properly dispose of it.
In the event you do decide to build your own designing, and building a functional waste storage and disposal system is in reality a bigger perplexing problem to overcome that will require a lot more thought than it would outwardly seem to get it right.
Maybe consider something suitable for your needs, after all we all soon realize there is enough work involved in cleaning and maintaining them. A couple to maybe consider.
2007 Myacht Pontoon Houseboat 45X15
1987 Sumerset 14x60 Houseboat