"Money won't be much of a problem as I will work up to this design over the years."
So, you are going to save up to a million bucks to build your 50' liveaboard lobster boat while working as a lobsterman? Where do I sign up?
Seriously, a 40' or even a 36' downeaster hull will give you decent living accommodations below. And half or less of the price of a 50', half or less of the fuel and half or less of the maintenance.
And I would suggest starting with a used recreational downeaster that you modify with a cutaway cabin and add a hauler. A lot easier than adding liveaboard systems to a plain jane lobster boat.
David