Alternative yacht idea, much more freedom:
This is the Christina O, which once belonged to Aristotle Onassis. She's one of THE classic motor yachts.
She also served in WWII as HMCS Stormont, a River class frigate.
Your job is to take a former naval vessel, and turn her into a luxury yacht. Ships from 1939 till modern day are allowed. Explain what you did, Keep parts of the superstructure, or remove everything over the main deck. if you kept the propulsion systems, engineering systems, or not. Is her displacement less?
You're allowed to take any naval vessel that was scrapped in the mentioned timeline, but remember that even though millionaires and later billionaires have deep pockets, they don't have bottomless pockets. Stay slightly
realistic. It's highly unlikely that you'd ever find someone to finance turning a heavy cruiser or an aircraft carrier into a yacht.